าง - มหาวิทยาลัยศิลปากร

EFFECTS OF MODIFIERS AND COMPATIBILIZERS ON PROPERTIES OF POLY(METHYL METHACRYLATE) BLENDS ม ส ด ุ อ ก ห ลาง ก ั น ำ ส By Miss Janyaporn Boromtongchoom A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree Master of Engineering Program in Chemical Engineering Department of Chemical Engineering Graduate School, Silpakorn University Academic Year 2012 Copyright of Graduate School, Silpakorn University EFFECTS OF MODIFIERS AND COMPATIBILIZERS ON PROPERTIES OF POLY(METHYL METHACRYLATE) BLENDS ม ส ด ุ อ ก ห ลาง ก ั น ำ ส By Miss Janyaporn Boromtongchoom A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree Master of Engineering Program in Chemical Engineering Department of Chemical Engineering Graduate School, Silpakorn University Academic Year 2012 Copyright of Graduate School, Silpakorn University ผลของสารชวยปรับปรุงและสารชวยผสมที่มีตอสมบัติของพอลิเมอรผสมพอลิเมทิลเมทาคริเลต ม ส ด ุ อ ก ห ลาง ก ั น ำ ส โดย นางสาวจรรยาพร บรมทองชุม วิทยานิพนธนี้เปนสวนหนึ่งของการศึกษาตามหลักสูตรปริญญาวิศวกรรมศาสตรมหาบัณฑิต สาขาวิชาวิศวกรรมเคมี ภาควิชาวิศวกรรมเคมี บัณฑิตวิทยาลัย มหาวิทยาลัยศิลปากร ปการศึกษา 2555 ลิขสิทธิ์ของบัณฑิตวิทยาลัย มหาวิทยาลัยศิลปากร The Graduate School, Silpakorn University has approved and accredited the Thesis title of “effects of modifiers and compatibilizers on properties of poly(methyl methacrylate) blends” submitted by Miss Janyaporn Boromtongchoom as a partial fulfillment of the requirements for the degree of Master of Engineering in Chemical Engineering ………........................................................................ (Assistant Professor Panjai Tantatsanawong, Ph.D.) Dean of Graduate School ม ส ด ุ อ ก ห ลาง ก ั น ำ ส ........../..................../.......... The Thesis Advisor Assistant Professor Sirirat Wacharawichanant, D.Eng. The Thesis Examination Committee .................................................... Chairman (Tarawipa Puangpetch, Ph.D.) ............/......................../.............. .................................................... Member (Associate Professor ML. Supakanok Thongyai, Ph.D.) ............/......................../.............. .................................................... Member (Supakij Suttiruengwong, Dr.Ing.) ............/......................../.............. .................................................... Member (Assistant Professor Sirirat Wacharawichanant, D.Eng.) ............/......................../.............. 54404204 : MAJOR : CHEMICAL ENGINEERING KEY WORDS : POLY(METHYL METHACRYLATE)/ POLYMER BLENDS/ COMPATIBILIZERS/ ETHYLENE COPOLYMER/ MODIFIERS JANYAPORN BOROMTONGCHOOM : EFFECTS OF MODIFIERS AND COMPATIBILIZERS ON PROPERTIES OF POLY(METHYL METHACRYLATE) BLENDS. THESIS ADVISOR : ASST. PROF. SIRIRAT WACHARAWICHANANT, D.Eng. 113 pp. This research studied the influence of modifiers and compatibilizers on the mechanical, thermomechanical, thermal and morphological properties of poly(methyl methacrylate) (PMMA) blends. In the experiment studied the blends of PMMA and two types of ethylene copolymers; ethylene-octene copolymer (EOC) and ethylenemethyl acrylate copolymer (EMAC), and PMMA blended with other polymers that was acrylonitrile-butadiene-styrene (ABS) and high density polyethylene (HDPE) at different compositions. The effects of compatibilizers were investigated in the PMMA/HDPE blends with varying content of three compatibilizers; EMAC, poly(ethylene-co-glycidyl methacrylate) (EGMA) and poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) (EMA-GMA). All polymer blends were prepared by melt blending in an internal mixer and were molded by compression method. In the PMMA/ABS blends, the results revealed that high ABS content over 40 %wt could improve the mechanical properties like impact strength, tensile strength and stress at break while low ABS content could improve the thermomechanical property. Moreover, the thermal stability of the blends increased with increasing ABS amount. The blends of PMMA and the two ethylene copolymers could enhance the impact strength at low copolymer content and also improve the thermal stability of the blends. The blends of PMMA/HDPE exhibited lower mechanical property while the thermal stability was improved when increased HDPE content. The addition of the EMAC compatibilizer led to better mechanical properties. The three compatibilizers did not enhanced thermomechanical and thermal property of these blends. ม ส ด ุ อ ก ห ลาง ก ั น ำ ส Department of Chemical Engineering Graduate School, Silpakorn University Student's signature........................................ Academic Year 2012 Thesis Advisor's signature........................................ d 54404204 : สาขาวิชาวิศวกรรมเคมี คําสําคัญ : พอลิเมทิลเมทาคริเลต/ พอลิเมอรผสม/ สารชวยผสม/ เอทิลีนโคพอลิเมอร/ สารปรับปรุง จรรยาพร บรมทองชุม: ผลของสารชวยปรับปรุงและสารชวยผสมที่มีตอสมบัติของ พอลิเมอรผสมพอลิเมทิลเมทาคริเลต. อาจารยที่ปรึกษาวิทยานิพนธ: ผศ.ดร.ศิริรัตน วัชรวิชานันท. 113 หนา. งานวิจัยนี้ศึกษาอิท ธิผลของสารชวยปรับปรุง และสารชวยผสมที่มีตอสมบัติทางกล สมบั ติท างกลเมื่อไดรับความรอน สมบัติท างความรอน และสมบัติทางโครงสรา งสัณฐานของ พอลิเมอรผสมพอลิเมทิลเมทาคริเลต ในการทดลองศึกษาพอลิเมอรผสมพอลิเมทิลเมทาคริเลตกับ เอทิลีนโคพอลิเมอรสองชนิด เอทิลีน-ออกทีนโคพอลิเมอรและเอทิลีน-เมทิลอะคริเลตโคพอลิเมอร และพอลิเมทิลเมทาคริเลตผสมพอลิเมอรชนิดอื่น ไดแก อะคริโลไนไตรล-บิวตะไดอีน-สไตรีน และพอลิเอทิ ลีนความหนาแนนสูง ที่ องคประกอบตา งๆกัน ผลของสารช วยผสมตรวจสอบใน พอลิเมอรผสมพอลิเมทิลเมทาคริเลตและพอลิเอทิลีนความหนาแนนสูงที่ปริมาณตางๆ ของสารชวย ผสมสามชนิด ไดแก เอทิลีน-เมทิลอะคริเลตโคพอลิเมอร พอลิเอทิลีน-โค-ไกลซิดิลเมทาคริเลต และ พอลิเอทิลีน-โค-เมทิลอะคริเลต-โค-ไกลซิดิลเมทาคริเลต พอลิเมอรผสมทั้งหมดเตรียมโดยวิธีผสม แบบหลอมเหลวในเครื่องผสมแบบปดและขึ้นรูปดวยวิธีอัดขึ้ นรูป ในพอลิเมอรผสมพอลิเมทิล เมทาคริเลตและอะคริโลไนไตรล -บิวตะไดอีน-สไตรีน ผลพบวาที่ปริมาณอะคริโลไนไตรล-บิวตะ ไดอีน-สไตรีนมากกวา 40 เปอรเซ็นตโดยน้ําหนัก สามารถปรับปรุงสมบัติทางกล เชน คาการตอทน แรงกระแทก การทนตอแรงดึงและความเคน ณ จุดแตกหัก ขณะที่ปริมาณอะคริโลไนไตรล -บิวตะไดอีน-สไตรีนต่ําสามารถปรับปรุงสมบัติทางกลเมื่อไดรับความรอน นอกจากนั้น ความเสถียรทาง ความรอนของพอลิเมอรผสมเพิ่มขึ้นเมื่อ เพิ่มปริมาณอะคริโลไนไตรล -บิวตะไดอีน-สไตรีน ใน พอลิเมอรผสมพอลิเมทิลเมทาคริเลตกับเอทิลีนโคพอลิเมอรสองชนิดสามารถเพิ่มคาความตานทาน แรงกระแทกที่ปริมาณโคพอลิเมอรต่ํา และปรับปรุงความเสถียรทางความรอนของพอลิเมอรผสม ได พอลิเมอรผสมพอลิเมทิลเมทาคริเลตและพอลิเอทิลีนความหนาแนนสูง แสดงสมบัติทางกลที่ ต่ําลง ในขณะที่ความเสถียรทางความรอนเพิ่มขึ้นเมื่อเพิ่มปริมาณพอลิเอทิลีนความหนาแนนสูง การ เติมสารชวยผสมเอทิลีน-เมทิลอะคริเลตโคพอลิเมอรทําใหสมบัติทางกลดีขึ้น สารชวยผสมทั้งสาม ชนิดไมไดเพิ่มสมบัติทางกลเมื่อไดรับความรอนและสมบัติทางความรอนของพอลิเมอรผสมนี้ ม ส ด ุ อ ก ห ลาง ก ั น ำ ส ภาควิชาวิศวกรรมเคมี บัณฑิตวิทยาลัย มหาวิทยาลัยศิลปากร ลายมือชื่อนักศึกษา........................................ ปการศึกษา 2555 ลายมือชื่ออาจารยที่ปรึกษาวิทยานิพนธ ........................................ e ACKNOWLEDGEMENTS The author wishes to express her sincere gratitude and appreciation to her advisor, Assistant Professor Dr. Sirirat Wacharawichanant for her immense support, stimulating, useful discussions throughout this research and devotion to revise this thesis otherwise it cannot be completed in a short time. In addition, the author would also be grateful to Dr. Tarawipa Puangpetch, as the chairman, Associate Professor Dr. ML. Supakanok Thongyai and Dr. Supakij Suttiruengwong as the members of the thesis committee for their kind and valuable suggestions that could be beneficially used to improve my work. The author also gratefully acknowledges the Center of Excellence on Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University for dynamic mechanical and thermogravimetric analysis. Many thanks for their useful advices and sincere assistances to Ms. Pannida Kijkobchai and Ms. Niramon Sa-nguanwong. Special thanks to all the members of Department of Chemical Engineering, Faculty of Engineering and Industrial Technology, Silpakorn University for their help and very kind support. Most of all, the author would like to express her highest gratitude to her parents and her sister who always pay attention to through these years for suggestions and morale support. With their greatest love and understanding so I can achieve my work as intended. The most success of graduation is devoted to my parents and my family. ม ส ด ุ อ ก ห ลาง ก ั น ำ ส f Table of Contents English Abstract ...................................................................................................... Thai Abstract .......................................................................................................... Acknowledgements ................................................................................................. List of Tables ......................................................................................................... List of Figures ......................................................................................................... Chapter 1 2 3 4 5 Introduction ………………………………………………………....... Theory ………………………………………………………………... Polymer blend ……………………...………………………….. Poly(methyl methacrylate) …………………………………….. High density polyethylene …………………………………….. Acrylonitrile-butadiene-styrene ……………………………….. Compatibilizers ……………………………...………………… Internal mixer ………………………...………………………... Compression molding …………………………...…………….. Mechanical property …………………………………………... Thermal analysis ……………………………...……………….. Thermomechanical analysis …………….……………………... Morphology analysis …………………………………………... Literature review ……………………………………………………... Property modifier in polymer blends ……………………...…... Compatibilizer in polymer blends …………………………....... Experimental procedure ……………………………………………… Materials ……………………………………………………….. Preparation of polymer blends ……………………………........ Sample preparation ……………………………………………. Sample characterization by Scanning Electron Microscopy …... Mechanical test …………………...…………………………… Thermomechanical analysis …………………………………… Thermal analysis ………………………………………………. Results and discussion Characterization of PMMA/ABS blends …………………….... Morphology …………………………...…...……………. Mechanical property ………...………………………...… Thermomechanical property ……...………………...…… Thermal property ……………………………...…...……. Characterization of PMMA/copolymer blends………………… Morphology ………………………………..……………. Mechanical property ……...………………………...…… Thermomechanical property …...………………………... Thermal analysis …………………………………...……. Effects of compatibilizer on PMMA/HDPE blends ……….…... ม ส ด ุ อ ก ห ลาง ก ั น ำ ส g Page d e f i j 1 3 3 4 5 6 7 10 10 11 14 15 17 19 22 29 29 30 31 33 33 35 35 37 37 37 39 44 44 47 47 47 53 55 58 Chapter 5 PMMA/HDPE and PMMA/HDPE/EMAC blends ……… Torque measurement ……………………………… Morphology ……………………………………….. Mechanical property ………………………………. Thermomechanical property……………….……… Thermal analysis ………………………………….. PMMA/HDPE blends with and without EGMA and EMA-GMA compatibilizer ……………………….. Torque measurement ……………………………… Morphology ……………………………………….. Mechanical property ………………………………. Thermomechanical property……………….……… Thermal analysis ………………………………….. 6 Conclusions Bibliography …………………………………………………………………... Appendix ………………………………………………………………………. Appendix A: Nomenclature ……………………………………….…. Appendix B: International proceeding ………………………………. Biography ม ส ด ุ อ ก ห ลาง ก ั น ำ ส h Page 58 58 59 63 67 68 73 73 78 85 89 95 99 100 107 108 111 113 List of Tables Tables 1 2 3 4 5 6 7 8 9 10 11 Page Materials …………………………………………………………... Glass transition temperature of PMMA/ABS blends at different composition …………………………………………………... Decomposition temperature of PMMA/ABS blends ……………… Glass transition temperature of PMMA/copolymer blends ……….. Decomposition temperature of PMMA/copolymer blends ……….. Steady torque of PMMA/HDPE and PMMA/HDPE/EMAC blends Melting temperature and percentage crystallinity of PMMA/HDPE and PMMA/HDPE/EMAC blends at different composition … Decomposition temperature of PMMA/HDPE and PMMA/HDPE/EMAC blends at different composition ……... Steady torque of PMMA/HDPE blends with and without EMAGMA and EGMA compatibilizer at different composition ….. Melting temperature and percentage crystallinity of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer ………………………………………………... Decomposition temperature of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer ………..…… ส ม ส ด ุ อ ก ห ลาง ก ั น ำ i 30 44 46 57 57 59 72 73 76 97 98 List of Figures Figures 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 17 19 20 21 22 23 24 25 26 27 28 29 30 Page EMAC structure …………………………………………………... EOC structure ……………………………………………………... Schematic illustration of four types of ethylene-octene copolymers EGMA structure …………………………………………………... EMA-GMA structure ……………………………………………... Compression molding sequence: (a) molding material is placed into open cavities; (b) the press closes the mold, compressing material in the hot mold for cure; (c) the press opens and molded parts are ejected from the cavities ………………….. Tensile stress-strain curves for several categories of plastic materials ……………………………………………………… Notched izod impact tests, ASTM D-265 schematic procedure…... Schematic of the DMA system for the measurement of the dynamic modulus and damping factor ……………………….. Common clamping geometries for dynamic mechanical analysis ... Schematic diagrams for step in this study ………………………… The molecular structure of compatibilizers ……………………….. Internal mixer ……………………………………………………... Compression molding machine …………………………………… Scanning electron microscope (MX 2000S Camscan Analytical) ... Universal tensile testing machine (LR 50k from Lloyd instruments) ………………………………………………...... Izod impact strength test (Zwick/material testing August-Nagelstr. 11.D-89079 Ulm) ……………………………………………. Dynamic mechanical analyzer (Pyris Diamond DMA, Perkin Elmer) ………………………………………………………... Thermogravimetric analysis (Model SDT Q600, TA Instruments, England) …………………………………...…………………. Differential Scanning Calorimetry (Pyris I, Perkin Elmer, USA) … SEM micrographs of the impact fracture surfaces of PMMA and ABS …………………………………………………………... SEM micrographs of the impact fracture surfaces of PMMA/ABS blends at various composition ……….…………………...….. SEM micrographs of the impact fracture surfaces of PMMA/ABS blends at different composition ………….…………………... Impact strength of PMMA/ABS blends …………………………... Young’s modulus of PMMA/ABS blends …………….…….......... Tensile strength of PMMA/ABS blends ………………………….. Stress at break of PMMA/ABS blends ……………………………. Stiffness of PMMA/ABS blends ………………………………….. Storage modulus of PMMA, ABS and PMMA/ABS blends ……... Decomposition temperature of PMMA/ABS blends at different composition …………………………………………………... ม ส ด ุ อ ก ห ลาง ก ั น ำ ส j 8 8 9 9 10 11 13 14 16 16 29 30 31 33 33 34 34 35 36 36 37 38 39 40 41 42 42 43 45 46 List of Figures Figures 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 Page SEM micrographs of PMMA/EOC blends ………………………... SEM micrographs of PMMA/EMAC blends ……………………... Impact strength of PMMA/EOC and PMMA/EMAC blends …….. Young’s modulus of PMMA/EOC and PMMA/EMAC blends …... Tensile strength of PMMA/EOC and PMMA/EMAC blends …….. Stress at break of PMMA/EOC and PMMA/EMAC blends ……… Percentage strain at break of PMMA/EOC and PMMA/EMAC blends ………………………………………………………… Storage modulus of PMMA/EOC and PMMA/EMAC blends at different composition ………………………………………… Temperature versus tan delta of PMMA/EOC and PMMA/EMAC blends at different composition …………………………….... Torque versus mixing time of PMMA, HDPE, and PMMA/HDPE blends with and without EMAC compatibilizer at different composition ………………………………………………….. SEM micrographs of (a) pure PMMA and (b) pure ABS ………… SEM micrographs of PMMA/HDPE blends at different composition …………………………………………...……… SEM micrographs of PMMA/HDPE (w/w) blends with EMAC 5 phr ………………………………………………………….. Impact strength of PMMA/HDPE blends with and without EMAC compatibilizer at different composition .................................... Young’s modulus of PMMA/HDPE blends with and without EMAC compatibilizer at different composition ……………... Tensile strength of PMMA/HDPE blends with and without EMAC compatibilizer at different composition ………….…………... Stress at break of PMMA/HDPE blends with and without EMAC compatibilizer at different composition ……………………… Percentage strain at break of PMMA/HDPE blends with and without EMAC compatibilizer at different composition …….. Storage modulus of PMMA/HDPE blends with and without EMAC compatibilizer at different composition ……………... Temperature versus tan delta of PMMA/HDPE blends with and without EMAC compatibilizer ………………………………. DSC graph of PMMA/HDPE blends at different compositions …... DSC graph of PMMA/HDPE/5phr EMAC blends at different composition …………..………………………………………. Torque versus mixing time of PMMA/HDPE (90/10) blends with and without compatibilizer …………………………………... Torque versus mixing time of PMMA/HDPE (80/20) blends with and without compatibilizer …………………………………... Torque versus mixing time of PMMA/HDPE (70/30) blends with and without compatibilizer …………………………………... ส ม ส ด ุ อ ก ห ลาง ก ั น ำ k 48 49 50 51 51 52 53 54 56 58 59 61 62 63 64 65 66 67 69 70 71 71 74 74 75 List of Figures Figures 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 Page Torque versus mixing time of PMMA/HDPE (60/40) blends with and without compatibilizer …………………………………... Torque versus mixing time of PMMA/HDPE (50/50) blends with and without compatibilizer …………………………………... SEM micrographs of PMMA/EGMA and HDPE/EGMA blends … SEM micrographs of PMMA/HDPE (w/w) blends with 3 phr of EGMA ……………………………………………………….. SEM micrographs of PMMA/HDPE (w/w) blends with 5 phr of EGMA ……………………………………………………….. SEM micrographs of PMMA/EMA-GMA and HDPE/EMA-GMA SEM micrographs of PMMA/HDPE (w/w) blends with 3phr of EMA-GMA …………………………………………………... SEM micrographs of PMMA/HDPE (w/w) blends with 5phr of EMA-GMA …………………………………………………... Impact strength of PMMA/HDPE blends with and without EMAGMA and EGMA compatibilizer at different composition ….. Young’s modulus of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer at different composition …………………………………………………... Tensile strength of PMMA/HDPE blends with and without EMAGMA and EGMA compatibilizer at different composition ….. Stress at break of PMMA/HDPE blends with and without EMAGMA and EGMA compatibilizer at different composition ….. Percentage strain at break of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer at different composition …………………………………………………... Storage modulus of PMMA/HDPE blends with and without EMAGMA compatbilizer at different composition ………………... Temperature versus tan delta of PMMA/HDPE blends with and without EMA-GMA compatibilizer at different composition .. Storage modulus of PMMA/HDPE blends with and without EGMA compatbilizer at different composition ……………… Temperature versus tan delta of PMMA/HDPE blends with and without EGMA compatibilizer at different composition …….. DSC graph of PMMA/HDPE blends at different compositions DSC graph of PMMA/HDPE/3phr EMA-GMA blends at different composition …………………………………………...……… DSC graph of PMMA/HDPE/5phr EMA-GMA blends at different composition ………………………………………………….. DSC graph of PMMA/HDPE/3phr EGMA blends at different composition ………………………………………………….. DSC graph of PMMA/HDPE/5phr EGMA blends at different composition ………………………………………………….. ม ส ด ุ อ ก ห ลาง ก ั น ำ ส j 75 76 78 79 80 81 82 83 84 85 86 87 88 90 91 92 93 94 95 95 96 96 CHAPTER 1 INTRODUCTION One of the most popular techniques to improve the properties of several polymers is blending technique, which blended two or more polymers together to get a new type of polymer that possessed better properties [1]. Polymer blending is a convenient way to overcome the limitations of some applications of polymers such as the insufficient mechanical properties by the combination of good properties of each component. Nowadays, the increment in commercial importance of polymer blends is enlarged because of the convenience of blending technique. Although, blending is an easy technique to achieve new types of polymer that possess desirable properties but the important things that should be taken into consideration when using this method is miscibility and compatibility between two or more polymers. However, different polymers are normally immiscible as the large molecules ensure that there is very little mixing entropy available. In addition, polymer interfaces are often adequately narrow that there is little entanglement between the different species. As entanglement is essential for strength in polymer systems, at the interfaces between two immiscible polymers are usually weak [2]. Several articles reported that polymer blends are mostly immiscible due to poor adhesion and strong interfacial tension between polymer phases [3, 4, 5, 6]. An easy way to resolve this incident is the addition of compatibilizer such as block or graft copolymer into the blend. There are three main roles of a compatibilizer in the blending process; decreases the interfacial tension between the blend components; inhibits the coalescence process of the dispersed phase; improves the interfacial adhesion in the solid state [7, 8, 9, 10, 11, 12]. Blending polymers in the presence of compatibilizer can modify the adhesion between two polymers, stabilize the morphology of polymer blends and enhance mechanical properties [5, 12, 13, 14]. This research interested in three type of polymers which possess different properties that consist of poly(methyl methacrylate) (PMMA), high density polyethylene (HDPE) and acrylonitrile butadiene styrene (ABS). PMMA is a useful polymer that has been used in a wide range of fields such as for engineering and electrical purposes, medical technologies, and optical applications. Property of PMMA is brittle with high strength, high modulus of elasticity and high surface hardness (scratch resistance). The prominent property of PMMA is transparent and colorless. As a general rule, the good atmospheric stability and clarity of acrylics have made them useful as high impact window panes and other see-through barriers important in industry [15]. PMMA is commonly used in place of glass because their transparent and light. Although PMMA has many advantages but it is not optimized to some applications such as when extreme strength is necessary, because it behaves in a brittle manner when loaded. There are many techniques for the property improvement ม ส ด ุ อ ก ห ลาง ก ั น ำ ส 1 2 of PMMA to obtain desired properties such as addition of plasticizers, fillers and making polymer blends [16]. Many recently work revealed that the mechanical property of various thermoplastics could be improved by blending with copolymers, especially ethylene copolymers [17, 18, 19, 20, 21]. In this work, the property improvement of PMMA was investigated by blending PMMA with two copolymers; ethylene-octene copolymer (EOC) and ethylene-methyl acrylate copolymer (EMAC). In addition, blending PMMA with tough polymers like HDPE and ABS was also studied. HDPE is a partially crystalline thermoplastic material which composed of very long unbranched hydrocarbon chains. HDPE has a good balance of chemical resistance, low temperature impact strength, light weight, low cost, and it is easy to process [6]. ABS is a two-phase rubbermodified material which consists of polybutadiene embedded in a matrix of styrene which has been copolymerized with acrylonitrile. These three monomers offer flexibility in tailoring the property profiles. ABS materials exhibit a balanced combination of toughness, tensile strength, dimensional stability, rigidity, heat resistance, low-temperature properties, surface hardness, chemical resistance, a wide temperature use range, and electrical insulating properties [22, 23]. Blending PMMA with ductile polymer such as HDPE and ABS is an alternative way for the property improvement of PMMA. Moreover, some researches revealed that the addition of methyl acrylate copolymers could enhance the property of polymer blends by increased the compatibility between two polymer phases [12, 24, 25]. So the use of compatibilizers to enhance the compatibility between each component and the desired property was also studied. Three compatibilizers were added in PMMA/HDPE blends; EMAC, poly(ethylene-co-glycidyl methacrylate) (EGMA) and poly(ethyleneco-methyl acrylate-co-glycidyl methacrylate) (EMA-GMA). The purpose of this work is to study the effects of property modifiers and compatibilizers on the mechanical, thermal and morphological properties of PMMA blends. PMMA blends with other polymers and varying content of property modifiers and compatibilizers were prepared by an internal mixer. The compatibility between the blends and phase morphology were studied by scanning electron microscopy (SEM) technique. The mechanical properties of polymer blends were investigated by tensile testing and impact testing. The thermomechanical properties of the blends were examined by dynamic mechanical analysis (DMA). The thermal properties were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). ม ส ด ุ อ ก ห ลาง ก ั น ำ ส CHAPTER 2 THEORY 2.1 Polymer blends Polymer blends are mixtures of structurally different polymers, including block and graft copolymer. A polymer blend has two definitions: The broad definition includes any finely divided combination of two or more polymers. The narrow definition specifies that there be no chemical bonding between various polymers making up the blend [26]. There are many variations of polymer blends, from simple binary mixtures to combinations of block copolymers and homopolymers, reactive compatibilized system, impact modified polymers and other system. Polymer blends may consist of two or more components and one or more phases, depending on component miscibility. In general, the resulting morphology is related to the melt viscosity and melt elasticity of the components at processing conditions (temperature, shear stresses and shear rates), interfacial tension, and control of coalescence during and after break-up of the droplets of the immiscible polymeric component. According to the above definition polymer blends can be divided into three basic groups which are miscible blends, partially miscible blends and immiscible blends [27, 28]. (i) Miscible blends: Miscibility is considered to be the level (scale) of mixing of polymeric constituents of a blend yielding a material which exhibits the properties expected of a single phase material. The few commercial polymer blends that show miscible behavior is characterized by a single stable phase, the presence of a single glass transition temperature (Tg) and uniformity on a scale of about 10 nm; their properties are usually the weighted average of the properties of the individual phases. Note: this does not imply or require ideal mixing, but will be expected to be mixed approaching the segmental scale of dimensions. Structure can still be expected in the 1-2 nm range and is often observed. (ii) Partially miscible blends: Polymer blend is considered partially miscible if there is existed phase separation but each polymer rich phase contains a sufficient amount of other polymer to alter the properties of that phase (e.g., the glass transition temperature). This distinct separate phase may result in continuous or dispersed morphologies. Blends that are homogeneous at some temperature may under other conditions phase separate and these are referred to as partially or nearly miscible blends. Most properties of these blends are intermediate or often lower than those of the individual components. (iii) Immiscible blends: A blend is considered immiscible if it is separated into phases comprised primarily of the individual constituents, which during compounding will contribute to the creation of a distinct microstructure and unique properties. Phase separation is also established from thermodynamic relationships. There are a variety of different ways of describing blends. The word “compatible” is often used to describe polymer blends from mechanical process that ม ส ด ุ อ ก ห ลาง ก ั น ำ ส 3 4 resist phase separation or give desired properties. Mechanical compatibility or compatibility is a general term used to imply useful properties of a polymer blend. Generally, the mechanical properties are employed as a reference to the degree of compatibility. Compatibilization of incompatible polymer blends is a major area of research and development. Some systems are made compatible by the addition of a third component that is a compatibilizer or emulsifier. The degree of compatibility is generally related to the level of adhesion between the phases and the ability to transmit stress across the interface. Microheterogeneous is a blend that comprised of a wide range of compositionally different phases. While the blend may exhibit a single glass temperature peak, it is comprised of a distribution of glass transition temperatures between the component values [29]. ม ส ด ุ อ ก ห ลาง ก ั น ำ ส 2.2 Poly (methyl methacrylate) PMMA macromolecule is based on a monomer that corresponds to an ethylene molecule with one hydrogen atom substituted by a methyl group (i.e.,CH3-) while the second hydrogen atom on the same carbon is replaced by an acetyl group (i.e.,CH3COO-) giving the basic monomer unit [-CH3-C(CH3)(COOCH3)-]n. The raw chemical intermediate used for making PMMA is 2-hydroxy-2-methyl-propanenitrile, which is prepared by reacting acetone with hydrocyanic acid according to the following reaction: CH3COCH3 + HCN —> (CH3)2C(OH)CN Afterwards, the 2-hydroxy-2-methyl-propanenitrile produced is reacted with methanol (CH3OH) to yield the methacrylate ester. Another former route consisted of reacting methylacrylic acid [CH2=C(CH3)COOCH3] directly with methanol. The polymerization reaction is initiated either by organic peroxides or azo catalysts to finally produce the PMMA macromolecule. The polymerization is highly exothermic as indicated by the evaluate enthalpy of reaction (58 kJ.mol-1). Therefore, the process requires fast heat removal from the reactor vessel by efficient cooling. Continuous or batch processes are used [15]. Commercial PMMA is found as syndiotactic in structure than atactic. On one scale of assessment it might be considered about 54% syndiotactic, 37% atactic and 9% isotactic. Reduction in the temperature of free-radical polymerization down to -78oC increases the amount of syndiotacticity to about 78%. Substituents on the Dcarbon atom restrict chain flexibility but, being relatively small, lead to a significantly higher Tg than with polyethylene. Differences in the Tg’s of commercial polymers (approx. 104oC), syndiotactic polymers (approx. 115oC) and anionically prepared isotactic polymers (45oC) are generally ascribed to the differences in intermolecular dipole forces acting through the polar groups. Because PMMA has polar structure, it does not have electrical insulation properties comparable with polyethylene. Since the polar groups are found in a side chain these are not frozen in at the Tg and so the polymer has a rather high dielectric constant and power factor at temperatures well below the Tg. This side chain, appears to become relatively immobile at about 20oC, giving a secondary transition point below which electrical insulation properties are significantly improved. The increase in ductility above 40oC has also been associated 5 with this transition, often referred to as the E–transition. Because of the polymers are unbranched (apart from the methyl and methacrylate side groups) the main difference between uncompounded commercial grades is in the molecular weight [30]. PMMA is one of the more brittle amorphous thermoplastic materials. It has glass transition temperature Tg of about 100oC. In the glassy state the molecular mobility is low and the polymer chains are not able to undergo large-scale molecular motions in response to rapidly applied external stresses or impacts. Therefore although it has relatively good global creep properties at ambient temperature, PMMA is brittle and notch sensitive. Property of PMMA is brittle with high rigidity, excellent transparency and low water adsorption. The advantages of PMMA are good thermal stability, insulation properties and high mechanical strength such as modulus of elasticity and hardness [31]. Main applications are guards and covers. As a general rule, the good atmospheric stability and clarity of acrylics have made them useful as high impact window panes and other see-through barriers important in industry. Various modifications are being made to alter the properties of the basic acrylic resins for specific services. However, these are not found in any great use in the industrial are to date. The upper temperature of usefulness is approximately 90oC. ม ส ด ุ อ ก ห ลาง ก ั น ำ ส 2.3 High density polyethylene High density polyethylene (HDPE) is composed of very long unbranched hydrocarbon chains. These pack together easily in crystalline domains that alternate with amorphous segments, and the resulting material, while relatively strong and stiff, retains a degree of flexibility. HDPE is a partially crystalline, partially amorphous thermoplastic material. The degree of crystallinity depends on the molecular weight, the amount of comonomer present, and the heat treatment given. The crystallinity of a given HDPE resin can be varied over a wide range by the rate of cooling from the molten state; slower cooling rates favor crystalline growth. The range of crystallinity for HDPE is normally 50-80 %. Most commercial fabrication processes cool from the melt at much faster rates; as a result, an article fabricated from HDPE rarely reaches the density quoted on a data sheet. Because the amount of crystallinity in HDPE is variable, HDPE can be considered as an amorphous polymer having a variable amount of crystalline filler [16]. Several commercial processes are used to produce HDPE. All employ more moderate pressures and most also use lower temperatures than the low density polyethylene (LDPE) processes. The Ziegler-developed process uses the mildest conditions, 200-400 kPa (2-4 atm) and 50-75oC, to polymerize a solution of ethylene in a hydrocarbon solvent using a titanium tetrachloride/aluminum alkyl-based coordination catalyst. After quenching the polymerized mixture with a simple alcohol, the catalyst residues may be removed by extraction with dilute hydrochloric acid or may be rendered inert by a proprietary additive. The product is almost insoluble in the hydrocarbon solvent, so is recovered by centrifuging and drying. The final product is extruded into uniform pellets and cooled for shipping to fabricators. The other processes all use catalysts placed on the surface of solid support to effect the polymerization of ethylene. This may be conducted in solution in a hydrocarbon solvent, such as in oil processes, or in the gas phase in a fluidized bed reactor. The pressures and temperatures used, 1-10 MPa and 90-300oC depending on the process, are higher in both cases than for the Ziegler process but much more moderate than 6 those used in the high-pressure process. The product recovers from the solution processes in a manner similar to that used for the Ziegler process [32]. HDPE has a good balance of chemical resistance, low temperature impact strength, light weight, low cost, and processability. HDPE is semi-rigid, translucent, very tough and weatherproof. Applications include electrical fittings, applied films, wheel arch linings, rigid air baffles and some sheet uses. The most important application is fuel tanks and bodywork [32]. 2.4 Acrylonitrile-Butadiene-Styrene (ABS) ABS is a two-phase rubber-modified material which is generally opaque or translucent and possesses high impact strength. ABS was developed by Dow Chemical in the 1940s as part of the research which made high impact polystyrene. Three main processes are used industrially to polymerize styrene with acrylonitrile and butadiene: (i) the oldest process which is performed by emulsion polymerization is the more polluting; (ii) suspension polymerization consists of blending together a rich-rubber medium with styrene-acrylonitrile; (iii) the continuous mass polymerization which does not use an aqueous medium is the preferred route because it generates less waste. ABS consists of rubbery particles of polybutadiene embedded in a matrix of styrene (or D-methyl styrene) which has been copolymerized with acrylonitrile. The three monomers (A, B and S) offer flexibility in tailoring the property profiles. Acrylonitrile provides chemical resistance, ageing resistance, hardness and rigidity, gloss and melt strength. Butadiene provides low temperature, ductility, flexibility and melts strength. Styrene provides processing ease, gloss and hardness. Producers can vary the relative amount of the three components to optimize certain properties to meet the different requirements for various applications. The versatility of ABS can be further enhanced by substituting styrene with alpha-methyl styrene, or other high heat co-monomers, to obtain higher heat resistance [15]. This materials exhibit a balanced combination of toughness, tensile strength, dimensional stability, rigidity, heat resistance, low-temperature properties, surface hardness, chemical resistance, a wide temperature use range, and electrical insulating properties. Probably the most notable property of ABS is its toughness and high impact strength at extreme temperatures which permit applications at temperatures of –40oC to +100oC. ABS also offers good electrical insulation, low water absorption and good resistance to most chemicals. As far as processing is concerned, ABS has a good melt-flow, low shrinkage and produces excellent surface finish. The main disadvantage of ABS is its poor solvent and fatigue resistance, poor UV resistance, unless protected, and maximum continuous use temperature is only around 70oC. Moreover, ABS darkens and embrittles with progressive outdoor exposure. The color change in ABS has been attributed to unsaturated carbonyl compounds. The instability of ABS is primarily due to the butadiene phase which contains many double bonds [33]. ABS is widely used for manufacture of housings for a wide range of consumer products. These include cameras, business equipment, TVs, vacuum cleaners, food mixers, telephone sets and audio equipment, and many more. Electrical and electronics applications include transformer housings and switches. Other applications for ABS include pipes, sports equipment, safety helmets, luggage, furniture, medical equipment, tubes and caps. Automotive is the most important market for ABS. Main ม ส ด ุ อ ก ห ลาง ก ั น ำ ส 7 applications included loudspeaker grilles, door handles, door trim, instrument panels and consoles. ABS is also used for exterior components, electrical parts such as navigation systems housing and a small amount is used under-the-bonnet [34]. 2.5 Compatibilizers The compatibilizer is a functionalized substance used to stabilize and prevent segregation of the polymer components in the polymer blend with desirable end properties. There are several strategies of compatibilization, e.g., (i) addition of a small quantity of a third component that either is miscible with both phases (a cosolvent), or is a precisely tailored copolymer whose one part is miscible with one phase and another with another phase (0.5-2 %wt, usually block-type, less frequency graft one); (ii) addition of a large quantity, d35 %wt, of a core-shell copolymer that behaves like a multi-purpose compatibilizer-cum-impact modifier; and (iii) reactive compatibilization, designed to enhance the domain interactions and generate finer morphology by creating chemical bonds between the two homopolymers during the compounding or forming processes [7]. There are three main roles of a compatibilizer in the blending process. Firstly, it decreases the interfacial tension between the blend components and so retards the formation of the Rayleigh disturbances on the generated threads of dispersed phase. The lower the interfacial tension, the longer the deformation tension exceeds the interfacial tension, the longer the stretching of the thread proceeds, the smaller the diameter of the resulting thread becomes, and. Consequently, the finer the size and dispersion of the generated dispersed phase. Secondly, it inhibits the coalescence process of the dispersed phase via steric stabilization during subsequent blending and is thus able to form and stabilize a finer morphology. Finally, it improves the interfacial adhesion in the solid state. This can be obtained either by ascertaining that an appropriate concentration of covalent bonds crosses the interface, by adding a compatibilizer that can act as an adhesive between two components, and/or by controlling the morphology, especially by inducing the phase co-continuity. The enhanced adhesion facilitates efficient stress transfer from one phase to the other phase and prevents cracks initiated at the interface from growth until the occurrence of catastrophic failure [35]. 2.5.1 Ethylene-methyl acrylate copolymer (EMAC) EMAC is a copolymer that has been used for many years to improve the interlayer adhesion of tie layers in multilayered flexible packaging. A key property of EMAC in this application is their excellent adhesion to many different types of polymer substrates. Furthermore, EMAC is often blown into film with very rubbery mechanical properties and outstanding dart drop impact strength. The latex rubber-like properties of EMAC film led to its use in disposable gloves and medical devices without the associated hazards to people with allergies to latex rubber. Because of their adhesive properties, EMAC copolymers are used in extrusion coating, coextrusions, and laminating applications as heat-seal layers. EMAC is one of the most thermally stable of this group, and as such it is commonly used to form hot and dielectric seals, as well in multi-extrusion tie layer applications [36]. The chemical structure of EMAC is shown in Figure 1 [37]. ม ส ด ุ อ ก ห ลาง ก ั น ำ ส 8 Figure 1 EMAC structure. This copolymer is also widely used as a blending compound with olefin homopolymers as well as with polyamides, polyesters, and polycarbonate to improve impact strength and toughness and either to increase heat seal response or to promote adhesion. EMAC is also used in soft blow-molded articles such as squeeze toys, tubing, disposable medical gloves, and foamed sheet. EMAC copolymers and ethylene ethyl acrylate (EEA) copolymer containing up to 8% ethyl acrylate are approved by the FDA for food packaging [36]. 2.5.2 Ethylene-octene copolymer (EOC) Unlike other ethylene-higher olefin copolymer systems, there is a long history of investigations of ethylene-octene copolymers which emphasize to high-ethylene contents EOC as shown in Figure 2 [38]. This copolymer possesses excellent flow characteristics and it can improve impact property of polypropylene (PP) and polyethylene (PE). Most published studied classify this copolymer in four type: (i) copolymers with densities below 0.89 g/cm3; (ii) copolymers with densities of 0.890.91 g/ cm3; (iii) copolymers with densities of 0.91 to 0.93 g/cm3; and (iv) copolymers with densities higher than 0.93 g/cm3 [39]. The models describing the supposed morphologies showed in Figure 3 [40]. Figure 2 EOC structure. 9 Figure 3 Schematic illustration of four types of ethylene-octene copolymers. 2.5.3 Poly(ethylene-co-glycidyl methacrylate) (EGMA) EGMA is an attractive copolymer which has been used as an impact modifier for engineering thermoplastics, such as poly(ethylene terepthalate) (PET), poly(phenylene sulfide) (PPS) and polyamides. Because the epoxy groups (glycidyl) in EGMA structure can react with carboxyl or hydroxyl functional groups provide reactive nature to EGMA as shown in Figure [41]. Moreover, as a result of its elastomeric nature, EGMA has been used as a compatibilizer fore thermoplastic/polyolefin blends such as PET/HDPE, PBT/PP and PA6/PP blends [42]. Figure 4 EGMA structure. 2.5.4 Poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) (EMAGMA) EMA-GMA is one of methyl acrylate based copolymer, which consists of three types of copolymers which are ethylene, methyl acrylate, and glycidyl methacrylate copolymers as shown in Figure 5 [43]. There are many applications in biology of copolymers based on GMA such as the binding of drugs and bio molecules and in electronics industries. In the polymeric fields, EMA-GMA can used as an effective toughness modifier in poly(butylene terephthalate) (PBT) blends [44]. Besides, EMA-GMA improved the impact strength and produced ductile fracture surface of the ABS/polyamide 6 blends [25]. 10 Figure 5 EMA-GMA structure. 2.6 Internal Mixer Internal mixer is a heavy-duty machine in which the materials to be mixed are strenuously worked and fused by one or more rotors designed so that all parts of the charge pass repeatedly through zones of high shear. Internal mixers are batch compounders consisting of two rotors inside of double C-shaped mixing chamber. They are usually counter-rotating and non-intermeshing. There are two main variants of the internal mixer, the tangential rotor design or “Banbury type” and the interlocking rotor design or “Intermix type”. Both designs consist of a roughly figureof-eight-shaped mixing chamber with a counter-rotating rotor in each section. The difference between the two mixers designs is in their mixing action which is related to the shape of the rotors used [45]. Depending on the model, the rotors may or may not intermesh. They have a ram or piston on top to force the feed into the chamber and are discharged via a drop door on the bottom. Small lab-scale internal mixers are often discharged by opening one of the sides. Each rotor has seals and bearings on the end frames that close off the mixing chamber. Internal mixers used to be driven by fixed speed, alternating current motors via reduction gears, but today they are usually equipped with variable speed motors for greater versatility. One rotor can be driven by the motor which turns the second via connecting gears, or, as is more popular for high torque applications, each rotor is driven independently by a larger gear box assembly. Temperature control occurs by fluid flow through channels within the metal chamber walls, rotors, and drop door, and optionally within the ram. The main advantage of internal mixers over mills is their increased rate of throughput, which for some materials can be up to an order of magnitude higher [45]. 2.7 Compression Molding The schematic of compression molding process is shown in Figure 6 [46]. The mold bottom half, containing one or more bottom cavities, is bolted to the bottom platen of the molding press. In this diagram an upward-closing press is shown. Compression molding can also be done in downward-closing presses. The mold halves are kept heated to about 150oC, more or less, depending on the plastic being molded. A metered charge of molding compound, granular or preformed, is placed in the open bottom cavities. The press is then actuated to close, generally fast upward movement (200 to 800 in./min) until the molding material contacts the upper mold half. Then the closing speed is reduced (0 to 80 in./min) as the material in the cavities is heated by the mold and becomes fluid. As the mold continues to close, the material 11 is forced to flow so as to fill the cavities. The metered charge contains about 3 to 5% more material than is required for the molded parts, including runner and cull. As the mold halves are moving together to fully close the cavities, the slight excess of material is squeezed out along the land surfaces, the flat areas sealing off the cavities and causing the plastic to be compressed for the polymerization or cure. The slight excess of material on the land area cures into a very thin flash, which is readily separated from the molded part following cure and removal of part from the mold [46]. 2.8 Mechanical properties Mechanical properties are properties with respect to the behavior of the material on the external force. Example of mechanical properties, consist of tensile strength, stiffness and ductility. These properties of materials are important for engineering applications significantly in order to use it properly and able to work efficiently and safely. Figure 6 Compression molding sequence: (a) molding material is placed into open cavities; (b) the press closes the mold, compressing material in the hot mold for cure; (c) the press opens and molded parts are ejected from the cavities. 2.8.1 Tensile test Tensile tests are performed for several reasons. The results of tensile are used in selecting materials for engineering applications. Tensile properties frequently are included in material specifications to ensure quality. Tensile properties often are 12 measured during development of new materials and processes, so that different materials and processes can be compared. Finally, tensile properties often are used to predict the behavior of a material under forms of loading other than uniaxial tension [47]. Tensile properties are the most important single indication of strength in a material. The force necessary to pull the specimen apart is determined, along with how much the material stretches before breaking. The tensile test measures the resistance of a material to a static or slowly applied force. The specimen sample is placed in the universal testing machine and a force F, called the load, is applied. Thus, the change in length of the specimen ('l) is measured with respect to the original length (l0). Information concerning the strength, Young’s modulus, and ductility of a material can be obtained from such a tensile test. When a tensile test is conducted, the both of ends of the specimen are firmly clamped in the jaws of a tensile testing machine, the jaws move apart at rates of 0.05, 0.2, 0.5, 2 or 20 inches per minute which pulling the sample from both ends and data recorded includes load or force as a function of change in length ('l). These data are then subsequently converted into stress and strain. The stress-strain curve is analyzed further to extract properties of materials (e.g., Young’s modulus, yield strength, etc.). The elastic modulus (modulus of elasticity or tensile modulus) is the ratio of the applied stress to the strain it produces in the region in which strain is proportional to stress. The modulus is essentially a measure of stiffness and is a very useful property to know, because parts should be designed so their behavior in normal use falls in the proportional region in which the modulus is measured. For some applications where almost rubbery elasticity is desirable, a high ultimate elongation may be an asset. For rigid parts, on the other hand, there is little benefit in the fact they can be stretched extremely long. There is great benefit in moderate elongation, however, since this quality permits rapid absorption of impact and shock. Thus, the total area under a stress/strain curve is indicative of overall toughness as represented in Figure 7 [48]. A material of very high tensile strength and little elongation would tend to be brittle in service [49]. Figure 7 Tensile stress-strain curves for several categories of plastic materials. 13 2.8.2 Impact test Impact tests are widely used to evaluate a material’s capability to withstand high velocity impact loadings. The most common impact tests are the Izod and the Charpy tests. The Izod test evaluates the impact resistance of a cantilevered notched bending specimen as it is struck by a swinging hammer. The Izod impact test indicates the energy required to break specimens under standard conditions. It is usually determined on the basis of a 1 inch specimen, although the specimen used may be thinner in the lateral direction. In the test, a sample is clamped in the base of a pendulum testing machine so it is cantilevered upward with the notch facing the direction of impact. The pendulum is released, and the force consumed in breaking the sample is calculated from the height the pendulum reaches on the follow-through [50]. The specimens for impact test can be prepared in two types that are notch and unnotched specimens. The use of a notch implies quite rigid conditions. The intention of the notch is to approximate end-use conditions; the notch serves as a stress concentrator (or stress riser). Concentrations of stress occur in molded plastic products, not just from nicks or other surface irregularities, but from plastic product design, sharp corners, and molded-in stress caused by the molding process conditions. The notch also dictates that the fracture be essentially unidirectional and not multiaxial like most real end-use type of impacts. The notch is an artificial crack; consequently, the Izod test is primarily measuring the energy to propagate a crack. Impact resistance mainly recognizes the energy needed to propagate the crack. Figure 8 shows two notched Izod impact test schematic procedures, Method “A” and Method “E” of ASTM Standard D-256, “Impact Resistance of Plastics and Electrically Insulating Materials [51].” All ASTM D-256 methods use a pendulum arm to deliver the impact to the specimen. Method “A” shows the specimen “V” notch facing the pendulum arm to deliver the striking force to the test specimen. Method “A” is the preferred notched Izod impact test procedure. Method “E” shows the specimen “V” notch located in the opposite direction (180oC) from the pendulum arm, and is thus eliminated as a stress concentrator. The test as run with engineering resins usually produces the notation NB (no break), a very limited piece of technical data. This unnotched Izod test is useful for reinforced and filled materials, especially for fiberglass reinforced compounds, which require little energy to crack [51]. Figure 8 Notched Izod impact tests, ASTM D-265 schematic procedures. 14 The Izod value is useful in comparing various types or grades of a plastic. In comparing one plastic with another, however, the Izod impact test should not be considered a reliable indicator of overall toughness or impact strength. Some materials are notch-sensitive and derive greater concentrations of stress from the notching operation. The Izod impact test may indicate the need for avoiding sharp corners in parts made of such materials. For example, nylon and acetal-type plastics, which in molded parts are among the toughest materials, are notch-sensitive and derive greater concentrations of stress from the notching operation so relatively low values on the notched impact test was observed [48]. 2.9 Thermal Analysis In the study of polymers and their applications, it is important to understand the thermal behavior in addition to mechanical properties. The polymer molecules comprise of repeating units (created via polymerization process) which the vibration, rotation and motion of these molecules can be occurred independently. The change in temperature had effects on the movement of polymer molecules which led to the variation in polymer properties. 2.9.1 Differential scanning calorimetry (DSC) DSC technique was developed by M. J. O’Neill and E.S. Watson in 1962. DSC is actually an instrument developed by Privalov and Monaselidze in the year 1964 to measure the heat capacity and energy precisely. The difference in heat flow between a reference and a sample helps the DSC to precisely measure the heat released or absorbed during the transition phase. DSC has become the method of choice for quantitative studies of thermal transitions in polymers. In DSC, a polymer sample and an inert reference are heated, usually in a nitrogen atmosphere, and thermal transitions in the sample are detected and measured. The sample holder most commonly used is a very small aluminum cup (gold or graphite is used for analyses above 800oC), and the reference is either an empty cup or a cup containing an inert material in the temperature range of interest, such as anhydrous alumina. Sample sizes vary from about 0.5 to about 10 mg. Sample and reference are provided with individual heaters, and energy is supplied to keep the sample and reference temperatures constant. In this case, the electrical power difference between sample and reference (d'Q/dt) is recorded. Data are plotted as d'Q/dt on the ordinate against temperature on the abscissa. Such plots are called thermograms. Although, d'Q/dt is not linearly proportional, it related to heat capacity. The major advantage of DSC is that peak areas of thermograms are related directly to enthalpy changes in the sample, hence may be used for measurements of heat capacities, heats of fusion, enthalpies of reactions, and the like [52]. 2.9.2 Thermogravimetric analysis (TGA) TGA is used primarily for determining thermal stability of polymers. Like DTA, TGA is and old technique but has been applied to polymers only since the 1960s. The most widely used TGA method is based on continuous measurement of weight on a sensitive balance (called a thermobalance) as sample temperature is 15 increased in air or in an inert atmosphere. This is referred to as nonisothermal TGA. Data are recorded as a thermogram of weight versus temperature. Weight loss may arise from evaporation of residual moisture or solvent, but at higher temperatures it results from polymer decomposition. Besides providing information on thermal stability, TGA may be used to characterize polymers through loss of a known entity, such as HCl from poly (vinyl chloride). Thus weight loss can be correlated with percent vinyl chloride in a copolymer. TGA is also useful for determining volatilities of plasticizers and other additives. Thermal stability studies are the major application of TGA, however. Residual weight is frequently an accurate reflection of char formation, which is of interest in flammability testing [52]. A variation of the method is to record weight loss with time at a constant temperature called isothermal TGA; this is less commonly used than non-isothermal TGA. Modern TGA instruments allow thermograms to be recorded on microgram quantities of material. Some instruments are designed to record and process DSC and TGA data simultaneously, and may also be adapted for gas chromatographic and/or mass spectrometric analysis of effluent degradation products [52]. 2.10 Thermomechanical Analysis Dynamic mechanical analysis (DMA) Dynamic mechanical analysis (DMA) is another thermal analysis technique used to obtain information on the curing of materials. DMA determines the temperature at which mechanical curing takes place as materials transition between a rubbery state to a glassy state. In dynamic mechanical analysis, specimens are subjected to oscillating loading. The time dependence of material behavior can be characterized by varying the frequency to acquire viscoelastic values over a wide frequency range. A schematic diagram of the DMA system is shown in Figure 9 [53]. Different clamping types could be used for particular specimens as shown in Figure 10 [54]. Single or dual cantilever bending modes are the most common for materials which can be formed into bars. Shear measurements are used for soft or thick materials. Films and fibers are always done on tension mode. Torsion measurements are normally done with a special design of instrument because most DMA’s can only exert a linear force rather than rotational force [54]. For a perfectly elastic material the strain response is immediate and the stress and strain are in phase. For a viscous fluid, stress and strain are 90o out of phase. Thus for polymers which usually exhibit viscoelasticity, the strain response lags behind the stress by some phase angle (G)--the loss angle--between 0o and 90o. The behavior can be represented by a complex modulus (or compliance) consisting of in-phase component (the storage modulus or compliance) and a 90o out-of- phase component, characterized by the loss modulus or compliance. The energy loss due to the viscous flow is given by the ratio of these moduli, which is the loss tangent (or tanG). Values of the dynamic moduli and tanG are both frequency and temperature dependent. Maximum loss, i.e. maximum damping, occurs in the transition region. Such changes are related to particular molecular motions in the polymer. Measurement of the dynamical mechanical behavior, e.g. by torsion pendulum, vibrating reed, forced vibration, non-resonance or elastic wave propagation methods, can give data over a very wide frequency range of 10-3-10-6 Hz and frequently provides the most sensitive method of detecting transitions and associated molecular motions [55]. 16 Figure 9 Schematic of the DMA system for the measurement of the dynamic modulus and damping factor. Figure 10 Common clamping geometries for dynamic mechanical analysis. Both solids and liquids can be analyzed via DMA. For liquid samples, the resin is impregnated onto a fiberglass braid. The resin-impregnated fiberglass braid is placed into the DMA’s single or dual cantilever sampling assembly so that the ends of 17 the braid are held rigid and the center clamp is modulated at a set frequency. The energy required to maintain the modulation is measured to obtain the storage modulus and loss modulus. Tan delta, a ratio of the storage and loss moduli, is also obtained. Solid composites can also be analyzed by forming or cutting them to the specified size for the DMA and analyzing the “bars” in the same apparatus [56]. 2.11 Morphology Analysis Scanning Electron Microscopy (SEM) Blending dissimilar polymers can design a variety of morphologies. Morphology control is very important for polymer blends. There are several methods to observe morphology of polymer blends. Scanning electron microscopy (SEM) is normally used to investigate polymer surfaces. In addition to providing high resolution topographical images of a specimen’s surface, it was realized that the SEM could also provide various different contrast modes, where information relating to things like surface voltage is embedded in its output signals [57]. Usually, SEM micrographs are obtained by collecting secondary electrons emitted upon bombarding the samples with high energy electrons. The focused beam of electrons was scanned on the surface of samples. The interaction between electron and sample produced various signals that can be detected. These signals and secondary electron image (SEI) gives information about the topography of the sample surface, including external morphology (texture), chemical composition, and crystalline structure and orientation of materials making up the sample. In most applications, data are collected over a selected area of the surface of the sample, and a two-dimensional image is generated that displays spatial variations in these properties. To obtain information of morphology in the bulk of material, it is necessary to remove the surface layer. Only when adhesion between the phases is poor, “new surface”, that reflects the bulk morphology can be created by fracturing the sample. Normally, to prevent plastic deformation, the sample is first annealed in liquid nitrogen then fractured. Another method of removing the surface layer is by etching. This process may be carried out by: (i) chemical etching, where one polymer is degraded using a chemical reaction and the reaction products can be removed from surface; (ii) solvent etching, to selectively dissolve one of polymers, (iii) ion beam etching, to preferentially degrade one of the polymers. The low molecular weight byproducts evaporate under high vacuum. The micrographs of high quality, similar to transmission electron microscopy (TEM), can be obtained by SEM observation of microtomed and stained surfaces [58]. CHAPTER 3 LITTERATURE REVIEW In this chapter several research about polymer blends were reviewed, including the property improvement of polymer blends and the use of compatibilizers in polymer blends. 3.1 Property modifier in polymer blends Da Silva A. L. N. et al. [59] investigated the influences of molecular structure and polyethylene elastomer (PEE) content on the thermal and mechanical properties of the blends which related to the melt rheology behavior of the polypropylene (PP)/PEE blends. The PP/PEE blends expressed a reduction of viscosity with increasing frequency which indicated the pseudoplastic behavior. This behavior was related to the increased in the average end-to-end distance between PP coils which led to the higher interaction between PP molecules. As PEE content increased, the Young’s modulus decreased and resulted in the lower crystallinity of the blends. The stress at break and the stress at yield point also decreased with increasing PEE content. The morphological studied showed that the phase continuity may occur in the blends containing 50 to 60 percent by weight of PEE. The addition of PEE did not change the crystallization behavior of the matrix, but the crystallinity and heat of fusion decreased with the increased in PEE content. Aróstegui A. et al. [60] studied the properties of PBT blends with different amount of two compatibilizers which are EOC and EGMA. The results revealed that the Tg value of poly(butylene terepthalate) (PBT) in PBT/EGMA and the Tg of EOC in PBT/EOC/EGMA blends did not change due to the low EGMA level. This incident confirmed the absence of EGMA in EOC-rich phase of ternary blends so EGMA will be dissolved in PBT. The addition of PEO or EGMA did not affect the crystallinity of PBT phase. The Young’s modulus and the yield stress of PBT/EOC blends decreased with increasing EOC content due to the elastomeric nature of EOC. Both the pure components and the blends broke during cold drawing indicated that the change in ductility was small, although the elongation at break was higher than that of pure PBT. The epoxy compatibilizer showed highest interfacial tension which gave lower ductility. The greatly increased in the impact strength can be achieved by the addition of only 5 percent by weight of EOC due to the smaller interfacial tension. Kontopoulou M. et al. [17] studied the rheology, morphology, thermal and mechanical properties of the blends between PP and ethylene-D-olefin copolymers (ECs). They found that the addition of both ethylene-D-butene (EBC) and ethylene-Doctene copolymers (EOC) could improve the ductility and impact strength of the blends. The results also revealed that the blend contained ECs showed high viscosity ratio but they did not find the coalescence when increasing EC contents. PP blended with EBC showed higher viscosity ratio and smaller particle size that resulted in better mechanical properties than blended with EOC. 19 20 Li C. et al. [61] investigated the mechanical and morphological properties of polycarbonate (PC)/EOC blends and found that when increasing EOC content the tensile strength and elongation at break of the blends decreased. The dispersed phase in the blends changed from the fine sphere to rod-like shape simultaneously. In a consideration of ionomer-addition, the mechanical properties of the PC/EOC blends could be improved with low content of an ionomer. Blended PC with an ionomer led to the degradation of PC. Kelnar I. et al. [43] investigated the blends of PBT with various types of elastomeric copolymers. The resulting blends showed the improvement in impact strength, modulus and toughness. The evident enhancement in mechanical properties was found in the blends with the compatibilizers that contained epoxy functional group in their structure; this group provided reactive compatibilization and caused refinement of particle size of the other component by increased viscosity. The best mechanical behavior was found in the system of PBT and polystyrene-co-glycidyl methacrylate (PS-co-GMA) blends, which showed the smallest dispersed size about 0.1 μm. Wang X. et al. [62] studied the effect of ionomers on mechanical properties and rheology of polyoxymethylene (POM) blended with methyl methacrylate-styrenebutadiene (MBS) copolymer. Two ionomers, ethylene-methacrylic acid copolymer ionized with sodium cation (EMA-Na) and zinc cation (EMA-Zn) were used as impact modifiers in the blends. The results observed the toughening effect of both ionomers to POM/ionomer blends and EMA-Na provided higher effect due to higher elasticity and stronger ionic interaction than EMA-Zn. In POM/MBS blends, the decrease of impact strength was observed. The addition of ionomer into POM/MBS blends resulted in larger impact strength, tensile strength and elongation at break with increasing ionomer content. This incident was attributed to the compatibilizing effect of both ionomers, which improved the interfacial tension between phases and produced better stress transfer. However, the interaction between POM and ionomer resulted in the increased in viscosity of the blends that led to the reduction of the crystallinity of POM. Hu Y. S. et al. [63] studied the crystallization behavior and morphological pattern of PP/ethylene copolymer blends and reported that copolymers of propylene and ethylene are miscible over a wide range of copolymer content. The propylene-rich copolymers gave the same crystal form when regardless of comonomer content. They also found that copolymers composition affects the total crystallinity and relative amount of PP D- and J- forms, while the comonomer content strongly affects the crystallization kinetics. Yan X. et al. [64] analyzed the brittle-ductile transition of PP/EOC blends. The morphology and phase structure of the blends were examined by SEM and SmallAngle Light Scattering (SALS) technique. The results revealed that when increase EOC content, the dispersed domain size and notched impact strength of the blends increased due to the higher concentration of dispersed phase, but the interparticle distance (ID) decreased. The transition from brittle to tough behavior in PP/EOC blends obtained by increasing EOC content and decreasing the surface-to-surface interparticle distance (W) on brittle-ductile transition. The mixing time had slightly effect on phase morphology and impact strength of the PP/EOC blends. 21 Shin K. et al. [65] examined the effect of branch length on the miscibility of the polyolefin blends containing linear polyethylene (LPE) and poly(ethylene-co-Dolefin). In the experiment LPE was blended with different EOCs (each EOC contain different 1-octane content). To compare the results with Rhee and Crist’s work which blended LPE with poly(ethylene-co-1-butene) (EB), the critical interaction parameter (Xc) and constant C from copolymer equation were calculated. In this calculation based on one C8 unit of EOC, so it is necessary to convert the results of Rhee and Crist from one C4 to be two C4 units. SEM images showed miscibility of the LPE/EOC blends at low-octene content EOCs, higher than 21 percent by weight of 1octene content in EOC led to phase separation in the blends. In comparison, EB is less miscible to LPE than EOC at the same molecular weight and weight fraction of comonomer. Selvakumar M. et al. [66] examined the miscibility of PMMA and polyethylene glycol (PEG) blends in tetrahydrofuran in the temperature range of 298313 K. The solution viscosity, ultrasonic velocity and refractive index of the blend solutions were analyzed for miscibility study. The positive interactions in the system indicated that the blends are miscible in all composition range. Moreover, heat of mixing showed very small effect of temperature on the miscibility of the blends. The Fourier transform infrared spectroscopy studies confirmed the presence of weak specific interaction, such as hydrogen bonding, which provide the miscibility of the blends. Svoboda P. et al. [67] investigated the blends of PP and EOC. They studied elastic properties of the blends from tensile test. They found that the PP/EOC blends exhibit good elastic behavior at low content of PP, not higher than 30 percent by weight. The best elastic properties found in the blends which the values of residual strain were similar to that of pure EOC. The elastic properties became worse when added more PP, because the shape of PP particles formed as an elongated structure and finally appeared as a co-continuous phase. Ryan D. et al. [68] studied the improvement of tensile properties of the blends of styrene-ethylene-propylene-styrene triblock copolymer (SEPS) and different content of polyamide 6 (PA6) up to 30 percent by weight in the presence of maleic anhydride (MAH)-modified compatibilizers. The addition of PA6 into the SEPS phase enhanced the resistance to irreversible deformation of SEPS. However, blending PA6 with SEPS was insufficient for improving retraction properties so the addition of compatibilizer was necessary. The results suggested that the incorporation of compatibilizers increased the intermolecular interaction between two polymer phases. This may be the consequence of two compatibilizing mechanisms, the reaction between PA6 amide group or amine end-group and MA group of the compatibilizer which produced chain scission in PA6 main chain and water, respectively. Moreover, tensile properties of the blends increased when used higher barrel temperature. This incident may be attributed to the better compatibilizing mechanisms due to a higher degree of reaction between MA and PA6 or the reduction of melt viscosity of the blends when higher temperature were used. Kunimune N. et al. [69] investigated the effect of reactive additive content and screw speed during extrusion on the properties of recycled polyethylene terepthalate (RPET). The results revealed that the impact strength increased as the density of the blends decreased. The tensile strength slightly increased with increasing 22 screw speed, but the impact strength showed contrary trend. For thermal properties, the addition of EGMA decreased the melting temperature of RPET/EGMA blends because of reactions between RPET and EGMA produced branches in polymer chains. Moreover, the reaction between carboxyl and hydroxyl groups of RPET with epoxy group of EGMA result in higher molecular weights of RPET, as observed from the higher viscosity. The toughness of the blends increased with increasing EGMA content, but the density of the blends became lower. The SEM images of the blends expressed ductile and microporous structures. The reduction of these microporous can be achieved by increasing screw speed in the blend process, which indicated better dispersion of EGMA in RPET. The increased in screw speed during the blend process also had an effect on the higher crystallinity and density of the blends which confirmed by the increased in viscosity. Siddaramaiah et al. [70] examined the mechanical and rheological properties of the blends of poly(ethylene acrylic acid) (PEA) and low density polyethylene (LDPE). The effects of LDPE content on the blends properties were studied. In case of flow behavior, the incorporation of LDPE into PEA increased the melting temperature and reduced the consistency index (K) of the blends. The melt viscosity of the blends in all composition decreased with increasing shear stress in all temperature range, which indicated to the pseudoplastic behavior of polymer blends. The activation energy of flow for PEA was higher than that of LDPE at all shear rates. The physicomechanical properties of PEA/LDPE blend lied between of their pure polymer component. The obtained data found that the optimum composition of blend fall in the range of PEA/LDPE 90/10-60/40 (weight by weight, w/w). 3.2 Compatibilizer in polymer blends Araújo E. M. et al. [24] studied the behavior of the properties improvement of ABS/PA6 blends with compatibilizers. The results revealed that the impact properties and morphology significantly improved when added poly(methyl methacrylate-co-maleic anhydride) (MMA-MAH) into the blends, this effect occurred due to the better interaction between ABS and PA6. They concluded that MMA-MAH was more effective than poly(methacrylate-co-glycidyl methacrylate) (MMA-GMA) in ABS and PA6 system. Zhang X. Q. et al. [71] studied the morphological and mechanical properties improvement of syndiotactic polystyrene (sPS)/PA6 blends by using maleic anhydride grafted syndiotactic polystyrene (sPS-g-MA) as a compatibilizer. The results from mechanical and morphological characterization revealed that the sPS/PA6 blends with compatibilizer showed higher impact strength which attributed to the improved adhesion between two polymer phases as observed from the reduction of dispersed PA6 domain size. The reactive compatibilizer sPS-g-MA was also affected the crystallization behaviors of both components in the blend that was confirmed by Fourier transform infrared spectrometer (FTIR) peak and DSC thermograms. Coltelli M.-B. et al. [72] investigated the addition of modified styrenebutadiene-styrene block copolymer (SBS) in the blends between very low density polyethylene (VLDPE) and PET. The SBS was functionalized with diethyl maleate and 2-hydroxyethyl methacrylate to obtain more reactive compatibilizer precursors, SBS-g-DEM and SBS-g-HEMA respectively. The morphology study revealed that the use of both type of SBS gave a drop-like morphology which refers to a better adhesion 23 between two phases than a coarse co-continuous morphology of PET/SBS 80/20 (w/w) blends. In the blend of PET with SBS-g-DEM or SBS-g-HEMA at the ratio of 20/80 by weight conceded the formation of similar amount of SBS-g-PET graft copolymer, despite of the lower functionalization degree of SBS-g-HEMA than that of SBS-g-DEM. Yordanov Chr. et al. [73] examined the fractionated crystallization of LDPE/PA6 75/25 (w/w) blends with different types of compatibilizers. The compatibilizer used were ethylene-co-acrylic acid (EAA), EGMA, and maleated polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymer (SEbS-g-MA). The results demonstrated that addition of 1-2 phr compatibilizers into the LDPE/PA6 blend caused a drastic reduction of droplet size. The strongest reduction of PA6 droplet size was found in the blends with SEbS-g-MA. The blends with SEbS-g-MA provided more pronounced fractionated crystallization than that of EAA, but this behavior did not observed in the blends compatibilized by EGMA. The results of Vickers microhardness test revealed that the used of compatibilizer caused a lower microhardness. The blends compatibilized with EAA and SEbS-g-MA exhibited larger decreased in microhardness than that of the blend with EGMA. From the obtained results suggested that the effectiveness of compatibilizer could be as follows: SEbS-g-MA > EAA > EGMA. Guerrica-Echevarría G. et al. [18] examined the influence of compatibilizer on the mechanical properties of the blends of poly(trimethylene terepthalate) (PTT) and EOC. In the experiment, EOC grafted with maleic anhydride (mEOC) were use as compatibilizers. SEM images revealed that PTT/mEOC blends composed by two immiscible amorphous phases and a partially crystalline mEOC phase. The compatibilization was observed by the reduction of the dispersed phase size that attributed to chemical reactions between maleic modification and the ester groups of PTT. The impact strength of PTT/mEOC blends tended to increase with increasing mEOC content in both low and high shear rate. Higher compatibilizer content led to a decreased in interparticle distance (ID) but also to a reduction in stiffness and strength. Kum C. K. et al. [74] investigated the compatibilization effect of poly (styrene-co-acrylonitrile)-grafted-PP (PP-g-SAN) on the blends of PP/ABS. The increased in mechanical properties were observed in the blend with PP-g-SAN copolymer, that may be due to toughening effect of ABS by improved the compatibility between PP and ABS with addition of compatibilizer, especially in PPrich composition. The results from complex viscosity were consistent with morphological and mechanical properties of the PP/ABS blends. The optimum content of PP-g-SAN copolymer was 3 part per one hundred part of polymer blends (phr). Ozkoc G. et al. [75] studied the properties of ABS/PA6 blends with and without two types of compatibilizers; EMA-GMA and ethylene-n-butyl acrylatemaleic anhydride (EnBACO-MAH). The effects of blend composition and compatibilizer content on polymer blends were examined. The results found that the EnBACO-MAH show higher efficiency than EMA-GMA. The ABS/PA 6 blends with compatibilizers gave lower melting point indicated the improvement in miscibility between the two polymers. The thermal properties of the blends was consistent with the mechanical properties that the addition of a proper amount of compatibilizers increased the yield strength, strain at break, especially the toughness of the blends. 24 Zhang C.-L. et al. [76] investigated the emulsification efficiency of graft copolymers and the influence of feeding mode on the emulsification efficiency in the system of polystyrene (PS)/PA6 blends. The morphology study revealed that PS was always the matrix and PA6 was the dispersed phase. The feeding mode had a strong effect on the dispersed domain size at short mixing time but this effect decreased at long mixing time. The three emulsifiers with similar in the PS backbone length and same in number of the PA6 graft but different in the PA6 graft length, the emulsification efficiency increased with increasing PA6 grafts. In case of two emulsifier with similar in both PS backbone and PA6 graft lengths but different in the number of PA6 graft, the emulsification efficiency showed small different. In term of blend composition, the dispersed phase domain size increased with increasing dispersed phase concentration which imply to the coalescence of minor phase. As the mass ratio between emulsifier and the dispersed phase increased, the coalescence decreased. Araújo J. R. et al. [1] studied the behavior of postconsumer polyethylene (PEpc)/PA6 blends that was prepared by varying the extrusion method and investigated the effects of compatibilizer on the properties of the blends. The results indicated that blending PEpc with PA6 by twin-screw extruder provided better mechanical properties than single-screw extruder. The melting enthalpy did not change with the addition of PEpc or polyethylene-graft-maleic anhydride (PE-gMAH). In case of morphological properties, they found that the domain size of dispersed phase decreased in the presence of PE-g-MAH. They concluded that blending PEpc with PA6 obtained good mechanical properties so it was an interesting alternative to make PEpc as a high-value product. Gururajan G. et al. [77] investigated the blends between polypropylene copolymer (PP-cp) and EMAC at different compositions. The presence of ethylene in the backbone structure of EMAC provided high compatibility with polyethylene. The results showed the reduction of yield stress and tensile strength of the films with increasing EMAC content due to the additive effect. In case of thermal properties, the crystallization temperature (Tc) of PP-cp in PP-cp/EMAC blend films showed a small decreased with increasing EMAC content indicated that EMAC decreased the nucleation rate. The morphology of the blend films showed a two-phase morphology that consists of rubbery elongated EMAC domains within PP-cp continuous phase. TEM images revealed finely dispersed EMAC domains which attributed to the viscosity ratio of EMAC to PP-cp. Moreover, EMAC can enhance the interaction of PP-cp with EMAC and produced better adhesion of the elastomers on the matrix polymer which results in larger tear strength. López-Quintana S. et al. [78] studied the addition of impact modifiers in the PA6 blends in the presence of compatibilizers. The maleated metallocene polyethylene (mPE) and metallocene ethylene-propylene (mEPR) were used as impact modifiers. Three types of maleic anhydride modified copolymers: a metallocene polyethylene (mPE-g-MAH), a metallocene ethylene-propylene copolymer (mEPR-gMAH), and an ethylene-propylene diene copolymer (EPDM-g-MAH) were used as compatibilizers. The obtained results revealed that the impact strength of both binary and ternary blends was improved with the incorporation of compatibilizers. The efficiency of grafted copolymers as impact modifier depends on the final morphology and the tensile properties of the blends. The most effective system which provided 25 high toughness and tensile modulus was the high-molecular weight PA6 blended with EPDM-g-MAH. Ozkoc G. et al. [25] studied the impact fracture toughness of ABS/PA6 blends with 5 percent by weight of two compatibilizers, carbon monoxide modified EnBACO-MAH and EMA-GMA. The notched Charpy impact tests were performed at room temperature according to ASTM D 256. The results revealed that the blends with both compatibilizers showed slower crack propagation indicated the higher energy absorption related to toughness behavior of ductile materials. The ABS/PA6 blends with EnBACO-MAH showed larger impact strength than that of the blends with EMA-GMA. The impact properties of the blends correspond to the morphology that EnBACO-MAH gave much smaller dispersed phase size. Starý Z. et al. [79] studied the influence of molecular structure of two compatibilizers, styrene-butadiene (SB) block copolymers and ethylene-propene (EPM) random copolymers, on the properties of LDPE/PS blends with the composition of 75/25 (w/w). The obtained results revealed that the blends with short PS blocks were located partly at the interface and partly in both bulk phases of the LDPE/PS blends and the copolymers form partitions inside PS particles. The copolymers with long PS blocks form as small nanoscale particles during melt mixing process. In the experiment, two types of EPMs with equal propene content but different viscosity were used. In addition, the SB copolymers with a low viscosity provided a high compatibilization effect with both types of EPMs. Moreover, the addition of SB copolymers with more viscous EPM to LDPE/PS blends led to a better impact strength. The most effective compatibilization system for LDPE/PS 75/25 (w/w) blends is the addition of EPM with higher viscosity and the triblock copolymer with short PS blocks. Lei Y. et al. [80] studied the effects of PE-g-MAH, triblock copolymer of styrene and ethylene-butadiene (SEBS), and 4,4’-methylenedi(phenyl isocyanate) (MDI) on properties of recycled HDPE (RHDPE) and recycled PET (RPET) blends. In case of RHDPE/RPET blends without compatibilizers, the linearly increasing with the increased of RPET content of flexural strength, flexural modulus, tensile strength, and tensile modulus were reported. However, these properties lied between those of neat RHDPE and RPET. When 5 percent by weight of SEBS was added, the crystallinity of RHDPE and RPET become lower, but higher impact strength was observed. The addition of 2 percent by weight of PE-g-MAH significantly reduced the RPET particle size which related to the lower interfacial tension and coalescence, indicated the enhancement of compatibility. The improved compatibility resulted in the better impact strength of the blends. Adding 0.5 percent by weight of MDI influenced morphology and provided larger tensile modulus but lowered tensile and impact strength. Lee H. G. et al. [5] examined the properties of PP/ABS blends with polypropylene-graft-maleic anhydride (PP-g-MAH). The mechanical properties of the blends were improved by addition of PP-g-MAH and showed the highest value when the droplet size of PP/ABS (70/30 w/w) blend showed a minimum value. The complex viscosity results were consistent with mechanical and morphological properties. The increase of mechanical strength was affected by the toughening effect of ABS in the PP/ABS blends. Moreover, the compatibility between PP and ABS was 26 improved by PP-g-MAH, and the optimum concentration of the compatibilizer was 3 phr). Lin Y. et al. [81] investigated the influence of the addition of compatibilizers into the blends of PP and 30 percent by weight of HDPE. Different types of copolymer were used as compatibilizer in this experiment included a multiblock ethylene-copolymer, two statistical EOC, two propylene-ethylene copolymers, and a styrene block copolymer (SBC). In all compatibilized blends, HDPE domain was dispersed in PP matrix and copolymers preferred to located at the interface between two polymer phases. The addition of copolymers did not decrease the HDPE domain size but resulted in the reduction of interface tension and increased interfacial adhesion. The used of these compatibilizers provided sufficient interfacial adhesion which can be observed from the ability of HDPE to yield and draw along with the PP matrix. Moreover, the ethylene-octene copolymer gave higher toughness than statistical ethylene-octene copolymer. Agrawal P. et al. [9] studied the properties of PA6/LDPE and PA6/HDPE blends by using three types of compatibilizer. The results from rheometrical and morphological properties confirmed that the addition of the compatibilizers to both PA6/LDPE and PA6/HDPE blends could improve the adhesion between two polymer phases and lead to better mechanical properties. In the PA6/LDPE blends, EMAGMA was the most effective compatibilizer. Both EMA-GMA and polyethylene grafted with acrylic acid (PE-g-AA) compatibilizers increased the compatibility between PA6 and HDPE. Filippone G. et al. [82] investigated the influence of the addition of modified organoclay (Cloisite® 15A) on the microstructure of the HDPE/PA6 blends. The blends ratio of HDPE/PA6 with 75/25 and 25/75 by weight with different content of organoclay were compared with the blends without any compatibilizer. SEM and TEM micrographs revealed that organoclay preferred to locate inside the PA6 phase, which more hydrophilic than HDPE phase. In addition, this occurrence also affected the viscoelastic behavior and steady-state shear viscosity of the host polymer. However, the microstructure of the blends were depended on whether the PA6 presences the major or minor phase. A small intercalation of polymer chains in between the silicate layers was found during melt mixing process. The incorporation of organoclay in the blends promoted the reduction in HDPE droplet size. When the filler was existed in the minor phase, the low content of organoclay lead to a refinement of the globular morphology but the higher organoclay loading than threshold produced the highly continuous structure of PA6 finely interpenetrate with the major HDPE phase. Mallick S. et al. [11] studied the morphological and mechanical properties of PMMA/HDPE blends. The results showed that the compatibility between PMMA and HDPE could improve by using nanoclay and PE-g-MAH as compatibilizers. The morphology showed the reduction of average domain size of dispersed phase when added the compatibilizers, especially PE-g-MAH. The results revealed that both compatibilizers increased the mechanical properties of the PMMA/HDPE (70/30 w/w) blends, but nanoclay was more effective than PE-g-MAH. Thermal properties were achieved by the incorporation of nanoclay in the blends. On the contrary, the PMMA/HDPE blends contained PE-g-MAH showed the decreased in thermal stability 27 which considered from the lower degradation temperatures than that of the PMMA/HDPE blends without PE-g-MAH. Scaffaro R. et al. [83] evaluated the effectiveness of different compatibilizer on the morphology behavior and mechanical properties of PA6/HDPE blends in the presence of 5 phr of organically modified montmorillonite (OMM). The compatibilizing systems that used in the experiment consist of EAA with 2,2’-(1,3phenylene)-bis(2-oxazoline) (PBO); HDPE modified with acrylic acid (HDAA) with PBO; and EGMA. SEM micrographs revealed that PA6/HDPE blends showed immiscible and incompatible morphology. The best morphology was obtained in the blends contained EAA/PBO which provided smaller dispersed domain size and better interfacial adhesion. Transmission electron microscopy (TEM) analysis showed that preferentially placement of clay in the PA6 phase and at PA6/HDPE interface. Furthermore, the addition of OMM gave higher elastic modulus but the highest value observed in the PA6/HDPE blends without compatibilizers. This incident probably occurred due to the interaction between compatibilizer and degradation products of the clay from thermo-oxidation during processing. Castillo-Castro T. E. et al. [84] studied the compatibilization effect of PE-gMAH in LDPE/n-dodecyl-benzene sulfonate doped polyaniline (PANIDBSA) blends. The thermal analysis explained the shift of thermal transitions of the blends that indicated the coupling agent improved the miscibility between two polymers. The additions of PE-g-MAH increased the conductivity and enhanced the mechanical properties, especially the ductility of the blends because the better interfacial compatibility. Coskunses F. I. et al. [85] examined the effects of compatibilizers, organoclay type and the blending sequence on the properties of LDPE-based blends. In the experiment, EMA-GMA and three types of clay were used as compatibilizer. The addition of 5 percent by weight of EMA-GMA exhibit the shift of characteristic diffraction peaks of nanoclay and LDPE/organoclay nanocomposite which indicated higher interlayer spacing of the clay layers. In LDPE/EMA-GMA/organoclay nanocomposite, the functional group in the compatibilizer increased the clay spacing and reduced the interaction between clay layers so intercalation and exfoliation was improved. SEM images revealed the well dispersion of organoclay in ternary blends which observed from shorter, circular and nonlinear crack propagation of the clays in the polymer matrix. Moreover, organoclay and compatibilizer did not affect the crystallization behavior of the nanocomposite. Dhibar A. K. et al. [86] investigated the cocontinuous phase morphology of PP/HDPE blends with the incorporation of small amount of organoclay, PE-g-MAH and SEBS. Two different blending methods were used in the experiment: one-step melted mixing of all components at 200oC for 15 minutes; and two-step melt mixing by gradually increased the temperature of internal mixer up to 200oC and hold for 15 minutes after melted mixing at 150oC for 10 minutes. The results showed that the cocontinuous morphology in PP/HDPE blends with clay occurred due to the change in heating protocol during melt blending. The intercalation of the clays by the HDPE chains was found only in the blends from two-step melt mixing. Regardless of the heating sequence in blending step, addition of PE-g-MAH or SEBS reduced the dispersed domain size of HDPE in the blends and the phase cocontinuity did not occurred without the clay. The SEM and TEM images represented the selective 28 dispersion of clays in minor phase (HDPE) before the melting of major phase (PP) in the second method that restrained the phase inversion process which led to cocontinuous structure in 75/25 and 80/20 w/w PP/HDPE blend with 0.5 phr of clay. Lin Y. et al. [87] examined the influence of the addition of block copolymers on the properties of PP/HDPE blends. Four types of ethylene-octene block copolymer (OBCs) which different comonomer compositions were used as compatibilizers in the blends. The morphology and mechanical properties of the PP/HDPE/OBCs blends were characterized by peeling blends microlayered tapes. Toughness of all OBCs compatibilized blends was significantly improved. The OBCs having higher adhesion strength also provided better mechanical properties for the compatibilized blends. The results also found that OBCs tended to concentrate at PP/HDPE interface which led to the reduction in the interfacial tension and the improvement in the interfacial adhesion. Gao J. et al. [88] studied the effects of the addition of silica (SiO2) nanoparticle on the phase morphology of the blends between PMMA and poly(styrene-co-acrylonitrile) (SAN). The rheology of the blends revealed that small amount of SiO2 nanoparticles produced the change in the moduli value but did not affected the temperature dependences of the blends. The results found that the PMMA/SAN blends ratio of 80/20, 70/30 and 60/40 w/w obeyed power law relation which indicated a co-continuous morphology. In contrast, the blends composition of 50/50 and 40/60 w/w exhibit droplet-matrix morphology. The addition of 3 percent by weight of SiO2 did not provide a drastic change in these morphological behaviors of the blends, but significantly shift the PMMA/SAN blend’s diagram into higher temperature. Yang H. et al. [89] investigated the compatibility improvement of polyamide66 (PA66)/ABS blends by the addition of maleic anhydride grafted polybutadiene (PB-g-MAH). The SEM micrographs showed binary phase structures of ABS dispersed in PA66 matrix, in the blends both with and without compatibilizer. The obtained results revealed that most of PB-g-MAH located at the interface of PA66/ABS by chain entanglement or chemical bonding with the two polymer phases. This incidence produced the reduction of interfacial tension and coalescence of ABS molecule including increased the interfacial adhesion. PB-g-MAH not only promoted the compatibility between PA66 and ABS phase but also improved the mechanical properties, impact strength and tensile strength, of the blends. CHAPTER 4 EXPERIMENTAL PROCEDURE This chapter describes the experimental procedures including the materials used in the experiment, the preparation of polymer blends and sample specimens, and the properties characterization of both pure polymers and all PMMA blends. The schematic diagram for step in this study was shown in Figure 11. Preparation of Materials Properties Testing Experimental Polymer Blending Step Samples Preparation Figure 11 Schematic diagrams for step in this study. 4.1 Materials Table 1 represents the properties of all polymers and copolymers using in this research. PMMA min was produced by Diapolyacrylate Company. HDPE was supplied by Thai Petrochemical Industry Public Company. ABS was supplied with the trade name of “INEOS” by INEOS ABS (Thailand) Company. Four types of compatibilizers were used in the experiment. Ethylene-octene copolymer (EOC) with was produced by Dow Chemical Company. Ethylene-methylacrylate copolymer (EMAC) was produced by DuPont Company. Poly(ethylene-co-glycidyl methacrylate) (EGMA) and poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) (EMA-GMA) was produced by Sigma-Aldrich Company. The molecular structures of compatibilizers are shown in Figure 12 [37, 39, 42, 44]. 29 30 Table 1 Polymer PMMA HDPE EMAC EMA-GMA EGMA Figure 12 Materials Ingredient Ethylene 75 %wt MA 25 %wt Ethylene 67 %wt MA 25 %wt GMA 8 %wt Ethylene 92 %wt GMA 8 %wt Density (g/cm3) Melt Index (g/10min) Tm (oC) Tg (oC) 1.18 0.97 5.7 15.0 130 110 - 0.94 0.5 90 - 0.94 6.0 39 - 0.94 5.0 99 - EOC EMAC EGMA EMA-GMA The molecular structure of compatibilizers. 4.2 Preparation of polymer blends 4.2.1 PMMA/EOC blends All types of polymers were dried before blending, PMMA was dried in an oven at 110oC for 4 h and EOC was dried at 80oC for 4 h. PMMA/EOC blends were prepared by melt blending in an internal mixer at 200oC and rotor speed of 50 rpm for 5 min as shown in Figure 13. The copolymer contents were 5, 10, 20 and 30 %wt. 4.2.2 PMMA/EMAC blends All types of polymers were dried before blending, PMMA was dried in an oven at 110oC for 4 h and EMAC was dried at 80oC for 4 h. PMMA/EMAC blends were prepared by melt blending in an internal mixer at 200oC and rotor speed of 50 rpm for 5 min. The copolymer contents were 5, 10, 20 and 30 %wt. 31 4.2.3 PMMA/ABS blends All types of polymers were dried before blending, PMMA was dried in an oven at 110oC for 4 h and ABS was dried at 80oC for 3 h. PMMA/ABS blends were prepared by melt blending in an internal mixer at 170oC and rotor speed of 50 rpm for 10 min. The ABS content in PMMA/ABS blends increment by 10 %wt from 10 to 90. 4.2.4 PMMA/HDPE blends with and without compatibilizer (1) PMMA/HDPE and PMMA/HDPE/EMAC blends All types of polymers were dried before blending, PMMA was dried in an oven at 110oC for 4 h, HDPE was dried at 110oC for 3 h and EMAC was dried at 80oC for 4 h. PMMA/HDPE and PMMA/HDPE/EMAC blends were prepared by melt blending in an internal mixer at 200oC and rotor speed of 50 rpm for 15 min. (2) PMMA/HDPE and PMMA/HDPE/compatibilizer blends All types of polymers were dried before blending, PMMA was dried in an oven at 110oC for 4 h and HDPE was dried at 110oC for 3 h. Two types of compatibilizer; EGMA and EMA-GMA were not dried before blending process. PMMA/HDPE, PMMA/HDPE/EGMA and PMMA/HDPE/EMA-GMA blends were prepared by melt blending in an internal mixer at 170 oC and rotor speed of 50 rpm for 15 min. Figure 13 Internal mixer. 4.3 Sample preparation 4.3.1 PMMA/EOC blends The samples for tensile and Izod impact test were done by compression molding at 180oC for 20 min as shown in Figure 14. Dumbbell samples for tensile test and rectangular samples for Izod impact test. DMA samples were prepared by compression molding at 180oC for 20 min and sample size was about 1.5x10x50 mm3. TGA and DSC samples were prepared as a film by compression molding at 180 oC for 5 min. 32 4.3.2 PMMA/EMAC blends The samples for tensile and Izod impact test were done by compression molding at 180oC for 20 min. Dumbbell samples for tensile test and rectangular samples for Izod impact test. DMA samples were prepared by compression molding at 180oC for 20 min and sample size was about 1.5x10x50 mm3. TGA and DSC samples were prepared as a film by compression molding at 180oC for 5 min. 4.3.3 PMMA/ABS blends The samples for tensile and Izod impact test were done by compression molding at 170oC for 15 min. Dumbbell samples for tensile test and rectangular samples for Izod impact test. DMA samples were prepared by compression molding at 170oC for 15 min and sample size was about 1.5x10x50 mm3. TGA and DSC samples were prepared as a film by compression molding at 170oC for 5 min. 4.3.4 PMMA/HDPE blends with and without compatibilizer (1) PMMA/HDPE and PMMA/HDPE/EMAC blends The samples for tensile and Izod impact test of PMMA/HDPE and PMMA/HDPE/EMAC blends were done by compression molding at 180oC for 20 min. Dumbbell samples for tensile test and rectangular samples for Izod impact test. DMA samples were prepared by compression molding at 180oC for 20 min and the sample size was about 1.5x10x50 mm3. TGA and DSC samples were prepared as a film by compression molding at 180oC for 5 min. (2) PMMA/HDPE and PMMA/HDPE/compatibilizers blends The samples for tensile and Izod impact test of PMMA/HDPE, PMMA/HDPE/EGMA and PMMA/HDPE/EMA-GMA blends were done by compression molding at 170oC for 15 min. Dumbbell samples for tensile test and rectangular samples for Izod impact test. DMA samples were prepared by compression molding at 170oC for 15 min and the sample size was about 1.5x10x50 mm3. TGA and DSC samples were prepared as a film by compression molding at 170oC for 5 min. Figure 14 Compression molding machine. 33 4.4. Sample characterization SEM observation The morphology of impact fractured specimens of PMMA blends were observed by SEM technique. SEM (MX 2000S Camscan Analytical) was employed to study the texture of fracture surface and the dispersion of the minor phase in the blends. SEM was performed in the back-scattered electron image (BEI) mode. The fractured surfaces of all the blending samples were sputter-coated with a thin layer of gold to enhance their conductivity before the examination as shown in Figure 15. Figure 1 Scanning electron microscope (MX 2000S Camscan Analytical). 4.5 Mechanical Test 4.5.1 Tensile test Tensile tests were performed according to ASTM D 638 using a universal tensile testing machine (LR 50k, Lloyd instrument) as shown in Figure 16. Tensile properties were obtained at room temperature with a crosshead speed of 50 mm/min. The dumbbell shaped specimens of all the blending samples were stretched at a constant speed until they fail. The tests were conducted to determine the properties such as Young’s modulus, tensile strength and elongation at break of the materials. Each value obtained represented the average of the results of five samples. 34 Figure 16 Universal tensile testing machine (LR 50k from Lloyd instruments). 4.5.2 Impact test Izod impact tests were conducted at room temperature according to ASTM D 256. The impact tester (Zwick/material testing August-Nagelstr.11.D-89079Ulm) was used with a pendulum of 4 J as shown in Figure 17. The rectangular samples were prepared by compression molding. The unnotched specimens were used in the test because the notched sensitive of PMMA. The notch was machined only for the pure HDPE and pure ABS samples. The Izod impact strength values were averaged from a series of five specimens. Figure 17 Izod impact strength tests (Zwick/material testing August-Nagelstr. 11.D- 89079 Ulm). 35 4.6 Thermomechanical Analysis DMA analysis The dynamic mechanical analyzer (DMA) was employed to investigate the dynamic mechanical properties of all polymer samples as shown in Figure 18. The tests were conducted over the temperature range of 30oC to 160oC at a frequency of 1Hz. The measurements were carried out with dual cantilever in bending mode. The blend specimens with a rectangular shape (size ~1.5x10x50 mm3) were prepared by compression molding. The viscoelastic properties, such as storage modulus (E’), loss modulus (E’’) and mechanical damping parameters (tanG) were measured as a function of temperature. Figure 18 Dynamic mechanical analyzer (Pyris Diamond DMA, Perkin Elmer). 4.7. Thermal Analysis 4.7.1 TGA analysis Polymer blends were subjected to TGA (STD Q600) to analyze the thermal stability of the samples. This instrument was located at Center of Excellence on Catalysis and Catalytic Reaction, Chulalongkorn University as shown in Figure 19. The polymer films obtained from compression molding method were cut into small pieces and approximately 5-10 mg of polymer samples were used in each scan. The samples then heated from 50oC to 600oC at a heating rate of 10oC/min under a nitrogen atmosphere. The thermal decomposition (% weight loss) of the samples was monitored and measured as a function of temperature. 36 Figure 19 Thermogravimetric analyzer (STD Q600). 4.7.2 DSC analysis Thermal behavior of PMMA blends were characterized by using a DSC (Pyris I, Perkin Elmer, USA) as shown in Figure 20. The polymer blend films were prepared from compression molded. The samples of a mass range between 6-8 mg were placed in aluminum pans. Thermal properties including glass transition temperature (Tg), melting temperature (Tm) and heat of fusion ('Hm) were determined. The measurement was carried out in a nitrogen atmosphere at a temperature range of 50oC to 180oC. DSC thermograms were recorded at a heating and cooling rate of 10oC/min. The details of the test consisted of seven steps which are shown as follows: 1. Hold for 1 min at 50oC 2. Heat from 50oC to 180oC at 10oC/min 3. Hold for 1 min at 180oC 4. Cool from 180oC to 50oC at 10oC/min 5. Hold for 1 min at 50oC 6. Heat from 50oC to 180oC at 10oC/min 7. Hold for 1 min at 180oC Figure 20 Differential scanning calorimeter (Pyris I, Perkin Elmer, USA). CHAPTER 5 RESULTS AND DISCUSSION This chapter describes the results of the characterization of PMMA/ABS blends, PMMA blends with copolymers (EOC, EMAC) and PMMA/HDPE blends with and without compatibilizers. 5.1 Characterization of PMMA/ABS blends 5.1.1 Morphology The impact fracture surfaces of PMMA/ABS blends were examined by SEM (MX 2000S Camscan Analytical) to study the blends morphology and the compatibility between two polymer phases. The morphology of pure PMMA and pure ABS is presented in Figure 21. As illustrated in the SEM images, the fracture surface of pure PMMA was quite smooth which indicated the brittle properties of PMMA. In contrast, pure ABS exhibited rough surface [90]. SEM micrographs of PMMA/ABS blends at different weight content of ABS are shown in Figure 22 and 23. In PMMArich compositions, the fracture surface of the blends were almost smooth with slightly tortuous. As the ABS content increased, the fracture surfaces of the blends became coarser which referred to higher toughness [62]. SEM micrographs seemed like onephase morphology in a whole range of composition which implied that PMMA and ABS was compatible. 20 μm 20 μm (a) Pure PMMA Figure 21 (b) Pure ABS SEM micrographs of the impact fracture surfaces of PMMA and ABS. 37 38 20 μm (a) PMMA/ABS 90/10 20 μm (b) PMMA/ABS 10/90 20 μm (c) PMMA/ABS 80/20 20 μm (d) PMMA/ABS 20/80 20 μm (d) PMMA/ABS 70/30 20 μm (e) PMMA/ABS 30/70 Figure 22 SEM micrographs of the impact fracture surfaces of PMMA/ABS blends at various compositions. 39 20 μm 20 μm (a) PMMA/ABS 60/40 (b) PMMA/ABS 40/60 20 μm (c) PMMA/ABS 50/50 Figure 23 SEM micrographs of the impact fracture surfaces of PMMA/ABS blends at different compositions. 5.1.2 Mechanical Properties 5.1.2.1 Impact property The unnotched Izod impact strength of PMMA/ABS blends was plotted as a function of ABS content as illustrated in Figure 24. The impact strength of PMMA/ABS blends contained 10-40 %wt of ABS was small decreased compared with pure PMMA. The impact strength increased with increasing ABS content from 50 to 90 %wt, and the value was also higher than that of pure ABS. This may be implied that PMMA/ABS blends possessed better stress transfer than the pure polymer [9]. The increased in impact strength was attributed to the toughening effect of ABS because the presence of a rubber phase in its microstructure [5, 23, 74]. In other words, the property modification of PMMA by blending with ABS could enlarge the capability of the blends to withstand the impact force. This result also related to the morphology of the blends, that PMMA and ABS showed almost one phase morphology which referred to the good compatibility between two polymers. When two polymers were blended together and obtained compatible blend, the 40 improvement in mechanical properties was achieved by the combination of the properties of individual polymer properties [70]. Although, the improvement in impact strength of PMMA was achieved by the addition of ABS but it required large quantity. Thus, it should be further developed for practical using. 45 Impact strength (mJ/mm2 ) 40 35 30 25 20 15 10 5 0 0 Figure 24 10 20 30 40 50 60 70 ABS content (%wt) 80 90 100 Impact strength of PMMA/ABS blends. 5.1.2.2 Tensile properties (1) Young’s modulus The Young’s modulus of PMMA/ABS blends at different composition is expressed in Figure 25. The results revealed that the Young’s modulus of PMMA/ABS did not change at low ABS loading (10-30 %wt). After these compositions the Young’s modulus of the blends tended to decrease as ABS content increased. However, the value of Young’s modulus of PMMA/ABS blends was laid between the two pure polymers. The decreased in the Young’s modulus with the rubber content was due to the rubbery nature of the dispersed ABS phase [18]. Because the stiffness of PMMA was greater than that of ABS which constituent of rubber, so the addition of ABS in PMMA resulted in lower Young’s modulus. 41 1400 Young's modulus (MPa) 1200 1000 800 600 400 200 0 0 Figure 25 10 20 30 40 50 60 ABS content (%wt) 70 80 90 100 Young’s modulus of PMMA/ABS blends. (2) Tensile strength The variation of tensile strength of PMMA/ABS blends at the different ratio of PMMA to ABS is represented in Figure 26. The results revealed that blended PMMA with ABS, the blends showed a small change in the tensile strength and it did not depend on the amount of ABS [91]. This could be observed from the graph that looks like a little wave which may be due to the elastomeric nature of ABS [69]. (3) Stress at break The effect of ABS amount on the stress at break of PMMA/ABS blends is shown in Figure 27. The stress at break of the blends showed similar trend to the tensile strength. All the blends exhibited a little change in the stress at break but did not vary with ABS content. Nevertheless, due to the elastomeric nature of ABS so the synergistic effect did not achieve at large ABS amount [92]. 42 100 Tensile strength (MPa) 80 60 40 20 0 0 Figure 26 10 20 30 40 50 60 ABS content (%wt) 70 80 90 100 Tensile strength of PMMA/ABS blends. 100 Stress at break (MPa) 80 60 40 20 0 0 Figure 27 10 20 30 40 50 60 ABS content (%wt) Stress at break of PMMA/ABS blends. 70 80 90 100 43 (4) Stiffness The stiffness of PMMA/ABS blends at various compositions was plotted with the amount of ABS according to Figure 28. The stiffness of PMMA/ABS blends exhibited a small change at low ABS content (10-30 %wt). At higher ABS amount than 30 %wt, the stiffness of PMMA/ABS blends was gradually decreased when increase ABS content. Nevertheless, the blends expressed higher stiffness than pure ABS along the composition range. It should be noted that stiffness referred to the ability of materials to resist deformation in response to applied force, so more flexible object possessed less stiff [93]. It could be clearly seen that pure PMMA had higher stiffness than pure ABS. This might be explained the lower stiffness of pure ABS that because it contained rubber in their molecules. Thus, the addition of ABS did not improve the stiffness of PMMA/ABS blends. 1200000 1000000 Stiffness (N/m) 800000 600000 400000 200000 0 0 Figure 28 10 20 30 40 50 60 ABS content (%wt) Stiffness of PMMA/ABS blends. 70 80 90 100 44 5.1.3 Thermomechanical properties The viscoelastic behavior of the PMMA/ABS blends and the two pure polymers was measured as a function of temperature by DMA. Figure 29 represents the storage modulus (E’) of PMMA, ABS and PMMA/ABS blends. The results revealed that the both the PMMA/ABS blends and the two polymers exhibited lower storage modulus as temperature increased. The sharply decreased was observed at the temperature higher than 90oC. It could be seen that at ABS content lower than 50 %wt, the blends expressed larger storage modulus when increased ABS amount. In the ABS-rich composition, the storage modulus tended to decreased with increasing ABS content. This indicated that the addition of small amount of ABS could improve the viscoelastic property of the PMMA/ABS blends. In addition, large ABS content led to the high elasticity so the lower storage modulus was observed. However, the PMMA/ABS blends showed a lower value of storage modulus than pure ABS. This could be described that ABS was inherently more elastic than PMMA because it contained rubber part in the structure so obtained blends expressed low storage modulus. 5.1.4 Thermal properties 5.1.4.1 DSC analysis The thermal properties of PMMA/ABS blends were investigated by DSC in the temperature range of 50-180oC. The effect of temperature on the thermal behavior of PMMA/ABS blends is illustrated in Table 2. Both PMMA and ABS was an amorphous polymer so the glass transition temperature was measured. PMMA/ABS blends also behaved as amorphous polymer as the two pure polymers. All the blends expressed one glass transition temperature and did not vary with the ABS content. This may be due to the Tg of pure PMMA was similar to the Tg of pure ABS so the ABS content did not affect the Tg of the blends. Moreover, the result from DSC was in good agreement with the results from DMA analysis. Table 2 Glass transition temperature of PMMA/ABS blends at different composition. Sample Pure PMMA PMMA/ABS 90/10 PMMA/ABS 80/20 PMMA/ABS 70/30 PMMA/ABS 60/40 PMMA/ABS 50/50 PMMA/ABS 40/60 PMMA/ABS 30/70 PMMA/ABS 20/80 PMMA/ABS 10/90 Pure ABS Glass transition Temperature (oC) from DSC Glass transition Temperature (oC) from DMA 109.4 110.6 110.8 108.3 109.5 110.1 110.8 111.0 110.8 109.1 109.9 112.0 111.9 111.5 110.9 109.9 111.6 112.1 113.2 113.0 110.5 110.9 45 3500000 PMMA PMMA/ABS 90/10 3000000 PMMA/ABS 80/20 PMMA/ABS 70/30 PMMA/ABS 60/40 PMMA/ABS 50/50 2500000 PMMA/ABS 40/60 PMMA/ABS 30/70 PMMA/ABS 20/80 2000000 E' (MPa) PMMA/ABS 10/90 ABS 1500000 1000000 500000 0 30 Figure 29 40 50 60 70 80 90 100 110 120 130 140 150 160 Temperature ( ๐C) Storage modulus of PMMA, ABS and PMMA/ABS blends. 46 5.1.4.2 TGA analysis TGA was employed to observe the thermal stability of the two pure polymers and PMMA/ABS blends. The decomposition (% weight loss) of the samples was monitored and recorded as a function of temperature. The temperature for each percent weight loss of the samples was an index that well reflected the heatdegradation resistance of the materials. The temperature of 5, 10 and 50% weight loss of each blend composition are illustrated in Table 3. It could be noticed the increase in the decomposition temperature of the PMMA/ABS blends when increased ABS content. The same results were found in every percentage weight loss of all samples as could be seen in Figure 30. Although, all the blends exhibited higher decomposition temperature than pure PMMA but it was still lower than that of pure ABS. Therefore, it may be inferred that the addition of ABS could enhance the thermal stability of the PMMA/ABS blends throughout composition range. Table 3 Decomposition temperature of PMMA/ABS blends. Sample Td5 338.3 350.0 354.4 355.7 359.0 359.7 363.4 355.4 367.6 369.6 377.3 Pure PMMA PMMA/ABS 90/10 PMMA/ABS 80/20 PMMA/ABS 70/30 PMMA/ABS 60/40 PMMA/ABS 50/50 PMMA/ABS 40/60 PMMA/ABS 30/70 PMMA/ABS 20/80 PMMA/ABS 10/90 Pure ABS Td10 348.3 359.5 362.6 365.4 368.9 370.4 373.7 365.4 380.5 382.5 390.5 Td50 373.9 383.3 387.9 390.6 395.4 399.2 402.5 390.4 408.5 411.6 417.6 Decomposition temperature (๐C) 500 450 400 350 300 Td5 250 Td10 200 Td50 150 100 50 0 0 Figure 30 10 20 30 40 50 60 70 ABS content (%wt) 80 90 Decomposition temperature of PMMA/ABS blends. 100 47 5.2 Characterization of PMMA/copolymer blends 5.2.1 Morphology The morphology study of PMMA/EOC and PMMA/EMAC blends was characterized by SEM technique. Both impact fracture surfaces and phase dispersion of the blends were analyzed. The SEM images of PMMA/EOC blends at the different amount of EOC are shown in Figure 31. The fracture surface of PMMA/EOC blends expressed that EOC form as spherical particles and dispersed in PMMA matrix. It can be clearly seen that when EOC content increased they spread out in the PMMA matrix. The average droplet size of dispersed phase at 10 %wt of EOC was 1.26 μm in diameter and became larger when EOC content increased. The average droplet size was 5.90 μm at 30 %wt of EOC. The poor adhesion was more evident when increased EOC content to 40 %wt which finally resulted in phase-separation. The SEM micrographs of fracture surfaces of PMMA/EMAC blends are represented in Figure 32. As shown in Figure 32(b), it seemed that at this composition the blends had only one phase, because obtained morphology was similar to the fracture surface of pure PMMA. This morphology may be occurred due to the good adhesion between surfaces of PMMA and EMAC. Considered at 20 %wt of EMAC, the effect of high copolymer content in PMMA matrix led to the aggregation of EMAC dispersed phase as a long structure as illustrated in Figure 32(d). When the EMAC contents reached 30 %wt, the dispersed phase cannot interfere into the PMMA matrix phase as shown in Figure 32(e). The formation of elongated structure may be due to high amount of copolymer [5]. The morphology investigation of both PMMA/EOC and PMMA/EMAC blends revealed that the one-phase morphology could be achieved by the addition of an only small amount of the copolymer. The higher loading of the copolymer provided the phase separation in the blends morphology. This incident became more apparent when the copolymer content exceeded 20 %wt. 5.2.2 Mechanical Properties 5.2.2.1 Impact property The Izod impact test had done on the unnotched specimens of both PMMA/EOC and PMMA/EMAC blends. The relationship between copolymer content and the Izod impact strength of the blends is represented in Figure 33. The impact strength of PMMA/EOC blends increased when 5 %wt of EOC were added and tended to decrease with increasing copolymer content. In case of PMMA/EMAC blends, the impact strength increased as the EMAC content increased until 10 %wt and then sharply decreased. The better impact strength of both PMMA/EOC and PMMA/EMAC blends at low content of the copolymer was attributed to the good compatibility between two phases [17] which led to the combination of the properties of each component [24, 25]. This could be observed from the improvement in the impact strength upon addition of an ethylene copolymer into the PMMA matrix. 48 20 μm 20 μm (b) PMMA/5%EOC (a) Pure PMMA 20 μm 20 μm (c) PMMA/10%EOC (d) PMMA/20%EOC 20 μm (e) PMMA/30%EOC Figure 31 SEM micrographs of PMMA/EOC blends. 49 20 μm (a) Pure PMMA 20 μm (b) PMMA/5%EMAC 20 μm (c) PMMA/10%EMAC 20 μm (d) PMMA/20%EMAC 20 μm (e) PMMA/30%EMAC Figure 32 SEM micrographs of PMMA/EMAC blends. 50 40 PMMA/EMAC 35 Impact strength (mJ/mm2) PMMA/EOC 30 25 20 15 10 5 0 0 Figure 33 5 10 15 20 Copolymer content (%wt) 25 30 Impact strength of PMMA/EOC and PMMA/EMAC blends. 5.2.2.2 Tensile properties (1) Young’s modulus Figure 34 represents the effect of copolymer content on the Young’s modulus of the blends of PMMA with two types of the copolymer. The results revealed that both PMMA/EOC and PMMA/EMAC blends showed a small increased in Young’s modulus at low copolymer content as 5 %wt. Young’s modulus of both blends became lower when the amount of copolymers was higher than 5 %wt. However, the blend contained EOC showed larger Young’s modulus than that of the blend with EMAC. This may be due to the elastomeric nature of ethylene copolymer which resulted in the reduction of Young’s modulus of the blends [92]. (2) Tensile strength The tensile strength of PMMA/EOC and PMMA/EMAC blends is presented in Figure 35. The results revealed that the tensile strength of PMMA/EOC blends decreased as EOC content increased. In case of PMMA/EMAC blends, the tensile strength of the blends did not change with the amount of EMAC at 5-10 %wt of EMAC. After these compositions, the tensile strength tended to decrease with the addition of higher amount of EMAC copolymer. It was known that the ductility of the blends was influenced by the nature of PMMA matrix and elastomeric copolymer content [92]. Although the addition of both copolymers in PMMA resulted in the lower tensile strength, but PMMA/EMAC blends exhibited slightly higher values than the blends contained EOC at low copolymer content. This may be due to better compatibility between PMMA and EMAC than EOC, because EMAC contained methyl acrylate segment in its structure. This result was in consistent with the morphology of the blends especially at low copolymer content. 51 1400 PMMA/EMAC Young's modulus (MPa) 1200 PMMA/EOC 1000 800 600 400 200 0 0 Figure 34 5 10 15 20 Copolymer content (%wt) 25 30 Young’s modulus of PMMA/EOC and PMMA/EMAC blends. 70 PMMA/EMAC Tensile strength (MPa) 60 PMMA/EOC 50 40 30 20 10 0 0 Figure 35 5 10 15 20 Copolymer content (%wt) 25 Tensile strength of PMMA/EOC and PMMA/EMAC blends. 30 52 (3) Stress at Break Figure 36 illustrates the effect of copolymer content on the stress at break of both PMMA/EOC and PMMA/EMAC blends. The stress at break of PMMA/EOC blends decreased as copolymer content increased. In contrast, PMMA/EMAC blends showed unchanged stress at break at low EMAC amount until 10 %wt. After these compositions, the stress at break trended to decrease with increasing EMAC content. In comparison, the stress at break of PMMA/EMAC blends was higher than that of PMMA/EOC blends at low copolymer content. This also may be due to the effect of better compatibility between PMMA and EMAC. 70 PMMA/EMAC Stress at break (MPa) 60 PMMA/EOC 50 40 30 20 10 0 0 Figure 36 5 10 15 20 Copolymer content (%wt) 25 30 Stress at break of PMMA/EOC and PMMA/EMAC blends. (4) Percentage strain at break The percentage strain at break of PMMA blends with both EOC and EMAC were plotted against a function of copolymer content which can be seen in Figure 37. The results revealed that both PMMA/EOC and PMMA/EMAC blends expressed lower percentage strain at break along range of composition. This may be inferred that the addition of an ethylene copolymer did not improve the elasticity of PMMA. 53 30 PMMA/EMAC PMMA/EOC Percent strain at break 25 20 15 10 5 0 0 Figure 37 5 10 15 20 Copolymer content (%wt) 25 30 Percentage strain at break of PMMA/EOC and PMMA/EMAC blends. 5.2.3 Thermomechanical Properties The investigation of thermomechanical properties of PMMA/EOC and PMMA/EMAC blends was accomplished by DMA. Storage modulus (E’) was plotted against a function of temperature at the different composition as shown in Figure 38. It could be seen that the storage modulus of PMMA/EOC and PMMA/EMAC blends exhibited the same trend in all compositions. PMMA/copolymer blends displayed significantly decreased in storage modulus when increased copolymer content. The lowest value of storage modulus found in the blends contained 30 %wt of copolymer. Moreover, the storage modulus of both blends was lower than that of pure PMMA. However, the PMMA/EOC blends expressed slightly higher storage modulus compared to the PMMA/EMAC blends in every composition. The low value of storage modulus indicated that the material was easily deformed when applied load. Thus, the addition of EOC and EMAC copolymer could not improve the viscoelastic property of the PMMA/copolymer blends. The lesser storage modulus at high copolymer content may be the consequence of the increased amount of soft rubber phase in the blends [92]. The clear different effect of copolymer types on the viscoelastic property of both blends did not notice because of the similarity of the structure between EOC and EMAC which contained ethylene group in their molecules. 54 3500000 PMMA PMMA/5%EMAC PMMA/10%EMAC 3000000 PMMA/20%EMAC PMMA/30%EMAC PMMA/5% EOC 2500000 PMMA/10%EOC PMMA/20%EOC PMMA/30%EOC E' (MPa) 2000000 1500000 1000000 500000 0 30 40 50 60 70 80 90 100 110 120 130 140 150 160 Temperature ( ๐C) igure 38 Storage modulus of PMMA/EMAC and PMMA/EOC blends at different composition. 55 The variation of tan delta of PMMA/EMAC and PMMA/EOC blends with temperature at different composition represents in Figure 39. It is known that tan delta is the ratio of the loss modulus (E’’) to the storage modulus (E’) of materials. The large tan delta value referred to the larger loss modulus relative to storage modulus which means that the deformation of the material occurred easily. The small tan delta value is related to the higher energy require to deformed the material because the good elastic property of that material [94]. In addition, the temperature at the peak of tan delta curve corresponds to the temperature at which maximum change in mobility of polymer chain occur, which defined as transition temperature (Tg) [94]. The results found that the tan delta of PMMA/EMAC blends tended to decrease with increasing EMAC content excepted in PMMA/5%EMAC which expressed lower value than at 10 and 20 %wt of EMAC. In PMMA/EOC blends, the value of tan delta was quite fluctuated but the tan delta of the blend contained 30 %wt of EOC still lowest. PMMA/EOC exhibited higher value of tan delta than PMMA/EMAC when compared at the same copolymer content excepted at 10 %wt. This mean that the addition of EMAC was more effective for the improvement of viscoelastic property of the PMMA/copolymer blends. The tan delta curve in Figure 39 revealed that the glass transition temperature of pure PMMA was noticed at 110.8oC. However, at temperature higher than 110.8oC, the apparent tan delta peak of both the PMMA/EMAC and PMMA/EOC blends was not observed. All the blends showed only small change in tan delta value. Thus, it could be implied that the addition of EMAC and EOC copolymer had slightly effect on the glass transition temperature of the PMMA/copolymer blends. This may be ascribed that the two copolymers mainly contained ethylene (semi-crystalline polymer) in their structure so it only little affects the glass transition of the blends. 5.2.4 Thermal Properties 5.2.4.1 DSC analysis The thermal behavior of PMMA and PMMA/copolymer blends with different composition were examined by DSC technique. The glass transition temperature of pure PMMA, PMMA/EMAC and PMMA/EOC blends were measured and tabulated in Table 4. Both copolymers showed the similar effect on the glass transition temperature of the blends. The PMMA/EMAC and PMMA/EOC blends exhibited higher glass transition temperature than the pure PMMA. However, the type of copolymer and copolymer content had no effect on the glass transition of the blends. This could be seen from similar glass transition temperature of each sample. 56 30 PMMA PMMA/5%EMAC PMMA/10%EMAC 25 PMMA/20%EMAC PMMA/30%EMAC PMMA/5%EOC PMMA/10%EOC 20 PMMA/20%EOC tan delta PMMA/30%EOC 15 10 5 0 30 40 50 60 70 80 90 100 110 120 130 140 150 160 Temperature ( ๐C) Figure 39 Temperature versus tan delta of PMMA/EMAC and PMMA/EOC blends at different composition. 57 Table 4 Glass transition temperature of PMMA/copolymer blends. Sample Pure PMMA PMMA/5%EMAC PMMA/10%EMAC PMMA/20%EMAC PMMA/30%EMAC PMMA/5%EOC PMMA/10%EOC PMMA/20%EOC PMMA/30%EOC Glass transition Temperature (oC) from DSC 110.2 116.4 115.9 117.1 116.7 Glass transition Temperature (oC) from DMA 110.8 117.5 116.9 117.1 117.2 117.3 117.3 117.2 116.7 117.5 117.8 115.2 118.3 5.2.4.2 TGA analysis The thermal stability of pure PMMA and PMMA blends with EMAC and EOC were also analyzed by TGA. The degradation of all samples of pure PMMA and PMMA/copolymer blends were measured at 5, 10 and 50 %weight loss as a function of temperature. The decomposition temperature at different % weight loss of each blends were tabulated in Table 5. The results revealed that both EMAC and EOC copolymer had an effect on the improvement in thermal property of the blends. The small increment of the decomposition temperature of the blends was noticed when weight content of copolymer increased. The same result was also found in every % weight loss. In comparison, the decomposition temperature of the PMMA/EOC blends slightly higher than that of the PMMA/EMAC blends especially at 20 %wt of copolymer. Furthermore, the decomposition temperature of the blend increased within a narrow range from 334oC to 343oC. The decomposition temperature of the blends displayed gradual improvements by 2-10oC over the pure PMMA in all blend composition. This could be inferred that the enhancement of thermal stability of PMMA was achieved by the addition of small amount of ethylene copolymer. Table 5 Decomposition temperature of PMMA/copolymer blends. Sample Td5 Td10 Td50 Pure PMMA PMMA/5%EMAC PMMA/10%EMAC PMMA/20%EMAC PMMA/30%EMAC 334.4 339.4 340.0 340.9 336.0 346.6 349.3 349.6 351.3 348.3 374.2 375.1 376.2 379.4 379.4 PMMA/5%EOC PMMA/10%EOC PMMA/20%EOC PMMA/30%EOC 334.4 339.0 342.8 339.9 346.6 350.5 351.8 351.0 374.2 377.2 378.2 381.3 58 5.3 Effects of compatibilizer on PMMA/HDPE blends 5.3.1 PMMA/HDPE and PMMA/HDPE/EMAC blends 5.3.1.1 Torque measurement It is known that the recording torque varying with time can provide the flow behavior of polymer blends, structure changes during processing and the influence of various additives. Moreover, the steady-state torque is referred to the melt viscosity for stabilized morphology which beneficial for product development and quality control [95]. The torque measurements were accomplished in an internal mixer. The blends were processed at 200oC with a rotor speed of 50 rpm, and a total mixing time of 15 min. Figure 40 shows the torque plots as a function of mixing time of PMMA/HDPE and PMMA/HDPE/EMAC blends at different composition. It should be noted that when the blend starts mixing, the torque will rise and reach a maximum when the plastics start melting. Then the torque will gradually decrease and reaches a steady-state after a short time [96]. This graph indicated that PMMA expressed highest torque value while the lowest value was observed in HDPE. The torques of PMMA/HDPE blends was laid between the two pure polymers and tended to decrease with increasing HDPE content. 40 PMMA HDPE PMMA/HDPE 90/10 PMMA/HDPE 80/20 PMMA/HDPE 70/30 PMMA/HDPE 60/40 PMMA/HDPE 50/50 PMMA/HDPE/EMAC 90/10/5 PMMA/HDPE/EMAC 80/20/5 PMMA/HDPE/EMAC 70/30/5 PMMA/HDPE/EMAC 60/40/5 PMMA/HDPE/EMAC 50/50/5 35 30 Torque (N.m) 25 20 15 10 5 0 0 1 2 3 4 5 6 7 8 Time (min) 9 10 11 12 13 14 15 Figure 40 Torque versus mixing time of PMMA, HDPE, and PMMA/HDPE blends with and without EMAC compatibilizer at different composition. Table 6 represents the steady torque of the two polymers and its blends. The steady torque of PMMA was much higher than HDPE indicated the more resistance to flow. Thus, the PMMA/HDPE blends expressed lower torque than pure PMMA. This indicated that HDPE could improve the flow behavior of PMMA. In 59 comparison, the blends with EMAC exhibited lower torque than PMMA/HDPE blends in every composition. The reduction of mixing torque after blending with EMAC may be the consequence of the better compatibility between PMMA and HDPE [97, 98]. In addition, it may be due to the increase of ethylene part in the blends, because EMAC consisting of ethylene group in their molecule. Table 6 Steady torque of PMMA/HDPE and PMMA/HDPE/EMAC blends. Sample PMMA PMMA/HDPE 90/10 PMMA/HDPE 80/20 PMMA/HDPE 70/30 PMMA/HDPE 60/40 PMMA/HDPE 50/50 PMMA/HDPE/EMAC 90/10/5 PMMA/HDPE/EMAC 80/20/5 PMMA/HDPE/EMAC 70/30/5 PMMA/HDPE/EMAC 60/40/5 PMMA/HDPE/EMAC 50/50/5 HDPE Steady torque (N.m) 10.7 8.8 5.5 4.3 3.3 2.4 8.2 5.3 3.3 3.0 2.3 1.2 5.3.1.2 Morphology The morphology and compatibility of PMMA/HDPE blends were analyzed from the SEM images. Figures 41(a) and 41(b) show the impact fracture surface of pure PMMA and pure HDPE respectively. The fracture surface of pure PMMA quite smooth which indicated the brittle property of PMMA. In contrast to the surface of PMMA, pure HDPE showed rough fracture surface which expressed the ductility of HDPE. 20 μm (a) Pure PMMA Figure 41 20 μm (b) Pure HDPE SEM micrographs of (a) pure PMMA and (b) pure HDPE. 60 The fracture surfaces and morphology of PMMA/HDPE blends with various ratios of PMMA to HDPE are represented in Figure 42. It can be observed that PMMA and HDPE were immiscible throughout range of composition even low content as 10 %wt of HDPE. This may be due to the polarity between the two polymers. The SEM micrographs indicated that PMMA was the matrix phase with dispersed HDPE phase. The incompatibility between PMMA and HDPE increased with increasing HDPE content from 10 to 50 %wt. This incident can be observed from the increased in diameter of dispersed phase size. The SEM micrograph revealed that the two-phase morphology was found in every blend compositions. There were two different surfaces in the SEM images. The smooth fracture surface implied to the brittle property of materials was PMMA phase. The rough surface referred to the ductility of the dispersed HDPE phase. At low HDPE amount as 10 to 20 %wt, HDPE dispersed phase form as spherical droplets spread in PMMA matrix as could be seen in Figure 42(a) and 42(b). At high HDPE content the structure of dispersed HDPE phase change to long structure due to large amount of HDPE in the blends as showed in Figure 42(c) to 42(e). The improvement of the compatibility between polymer phases may be achieved by the modification with compatibilizer, which could enhance the adhesion between polymer phases and inhibited the coalescence of the dispersed phase [8, 13,99]. Thus, the addition of compatibilizer to improve the properties of polymer blends was also studied. The effects of compatibilizer on the properties of the PMMA/HDPE blends were analyzed by the incorporation of 5 phr of EMAC. SEM micrographs in Figure 43 represent the impact fracture surfaces of PMMA/HDPE blends with EMAC 5 phr at different content of HDPE. Similar to the fracture surfaces of PMMA/HDPE blends that the blends with EMAC compatibilizer consisted of two different parts; smooth and rough surface which referred to PMMA and HDPE phase, respectively. In comparison, the morphology revealed that the HDPE dispersed domain size in PMMA/HDPE/EMAC blends quite smaller than in the PMMA/HDPE blends. Moreover, at low HDPE content as 10 to 30 %wt the evident reduction in the dispersed phase size was observed. This incident was the consequence of the addition of EMAC compatibilizer. EMAC acted as a compatibilizer which played an important role on the modification of the compatibility between PMMA and HDPE. This may be explained that small amount of EMAC can improve the adhesion between two polymer surfaces [9]. The reduction of dispersed phase size in the blends was related to the decrease of interfacial tension between PMMA and HDPE phase. 61 20 μm 20 μm (b) PMMA/HDPE 80/20 (a) PMMA/HDPE 90/10 20 μm (c) PMMA/HDPE 70/30 20 μm (d) PMMA/HDPE 60/40 20 μm (e) PMMA/HDPE 50/50 Figure 42 SEM micrographs of PMMA/HDPE blends at different composition. 62 20 μm 20 μm (a) PMMA/HDPE/EMAC 90/10/5 (b) PMMA/HDPE/EMAC 80/20/5 20 μm (c) PMMA/HDPE/EMAC 70/30/5 20 μm (d) PMMA/HDPE/EMAC 60/40/5 20 μm (e) PMMA/HDPE/EMAC 50/50/5 Figure 43 SEM micrographs of PMMA/HDPE (w/w) blends with EMAC 5 phr. 63 5.3.1.3 Mechanical properties (1) Impact property Figure 44 represents the Izod impact strength of PMMA/HDPE and PMMA/HDPE/5phr EMAC blends at different HDPE content. The results revealed that the impact strength of PMMA/HDPE blends tended to decrease with increasing HDPE amount. Moreover, the PMMA/HDPE blends exhibited lower impact strength than pure PMMA. This incident was in consistent with the blends morphology that that PMMA and HDPE were immiscible as could be seen from the two-phase morphology which occurred due to the poor adhesion between the two polymers. In PMMA/HDPE/5phr EMAC blends, the impact strength decreased as HDPE content increased. However, the blends contained EMAC expressed higher value of impact strength than PMMA/5phr EMAC blend at low HDPE content (10 to 20 %wt). The addition of EMAC compatibilizer markedly improved the impact strength of PMMA/HDPE blends throughout composition range. The results indicated that EMAC compatibilizer could increased the adhesion between PMMA and HDPE phases which resulted in the better impact property compared to the PMMA/HDPE blends without compatibilizer [4, 24, 100]. This obtained result was in good agreement with the morphological study that better compatibility between the two polymers phases could be achieve by the addition of EMAC compatibilizer which confirmed by the reduction of dispersed phase size. 30 PMMA/HDPE (200C) Impact strength (mJ/mm2 ) 25 PMMA/HDPE/5phr EMAC 20 15 10 5 0 0 10 20 30 HDPE content (%wt) 40 50 Figure 44 Impact strength of PMMA/HDPE blends with and without EMAC compatibilizer at different composition. 64 (2) Tensile property Young’s modulus The Young’s modulus of PMMA/HDPE blends with and without EMAC compatibilizer at various ratios of PMMA to HDPE is represented in Figure 45. The results found that the Young’s modulus of PMMA/HDPE blends gradually decreased with increasing HDPE content and the value also lower than pure PMMA. The blends contained 5 phr of EMAC showed the similar trend to the PMMA/HDPE blends that the Young’s modulus decreased as HDPE amount increased but the value was higher than that of the PMMA/5phr blends. However, the blends with EMAC provided larger Young’s modulus than the blends without compatibilizer in every blend compositions. This result indicated that the EMAC compatibilizer could improve the compatibility between blend components by increasing the interfacial adhesion which resulted in the better mechanical properties [1, 14, 71]. This incident was in agreement with the blends morphology. 2000 PMMA/HDPE (200C) 1800 PMMA/HDPE/5phr EMAC Young's modulus (MPa) 1600 1400 1200 1000 800 600 400 200 0 0 10 20 30 HDPE content (%wt) 40 50 Figure 45 Young’s modulus of PMMA/HDPE blends with and without EMAC compatibilizer at different composition. Tensile strength The tensile strength of PMMA/HDPE blends with and without EMAC compatibilizer was plotted against HDPE content as shown in Figure 46. The results found the reduction in the tensile strength of PMMA/HDPE blends when increased HDPE amount and the value were also lower than that of the pure PMMA. The tensile strength of PMMA/HDPE/5phr EMAC blends tended to decrease when added higher 65 Tensile Strength (MPa) HDPE content. In comparison, the blends contained EMAC expressed larger tensile strength than PMMA/HDPE blends. This was the consequence of the better adhesion between PMMA and HDPE which achieved by the addition of EMAC compatibilizer. The result was in consistent with the blends morphology that the compatibility between two polymers was improved by the addition of EMAC as could be seen from the smaller dispersed phase size, especially at low HDPE content. The good adhesion between blends components also led to the better mechanical properties [4]. 80 PMMA/HDPE (200C) 70 PMMA/HDPE/5phr EMAC 60 50 40 30 20 10 0 0 10 20 30 HDPE content (%wt) 40 50 Figure 46 Tensile strength of PMMA/HDPE with and without EMAC compatibilizer at different composition. Stress at break The stress at break of PMMA/HDPE blends with and without EMAC compatibilizer at different ratios of PMMA to HDPE was plotted in Figure 47. This graph showed the similar trend to the previous results of tensile strength. The gradually decreased in the stress at break of PMMA/HDPE blends was observed when increased amount of HDPE in the blends. The stress at break of the PMMA/HDPE with 5 phr of EMAC also tended to decreased when added higher HDPE content. It could be seen that the blends with compatibilizer exhibited larger value of stress at break than PMMA/HDPE blends in every composition. The addition of EMAC compatibilizer could enhance the adhesion and reduced the interfacial tension between PMMA and HDPE phases [89, 101]. Therefore, it could be deduced that the improvement in stress at break of the blends caused by the good compatibility between the two polymers, made by the presence of compatibilizer. This result was 66 Stress at Break (MPa) confirmed by the reduction of dispersed phase size as observed from the blends morphology. 80 PMMA/HDPE (200C) 70 PMMA/HDPE/5phr EMAC 60 50 40 30 20 10 0 0 10 20 30 HDPE content (%wt) 40 50 Figure 47 Stress at break of PMMA/HDPE blends with and without EMAC compatibilizer at different composition. Percentage strain at break Figure 48 showed the percentage strain at break of PMMA/HDPE blends with and without EMAC compatibilizer at different ratios of PMMA to HDPE. The results revealed that the percentage strain at break of PMMA/HDPE blends slightly change with HDPE content but the value was lower than that of pure PMMA. The PMMA/HDPE/5phr EMAC blends showed a very small change in the percentage strain at break with the variation of HDPE amount. This could be implied that the addition of HDPE had slightly effect on the percentage strain at break of the PMMA/HDPE blends although in the presence of compatibilizer. 67 20 PMMA/HDPE (200C) Percentage Strain at Break PMMA/HDPE/5phr EMAC 15 10 5 0 0 10 20 30 HDPE content (%wt) 40 50 Figure 48 Percentage strain at break of PMMA/HDPE blends with and without EMAC compatibilizer at different composition. 5.3.1.4 Thermomechanical Properties The thermomechanical property of PMMA/HDPE blends with and without EMAC compatibilizer was examined by DMA. The variation of storage modulus of the PMMA/HDPE and PMMA/HDPE/5phr EMAC blends at different composition was measured as shown in Figure 49. The storage modulus of pure PMMA tended to decreased when the temperature increased and then sharply decreased after 90oC. The storage modulus of pure HDPE gradually decreased with increasing temperature throughout the test. The PMMA/HDPE blends also showed a reduction of the storage modulus as temperature increased. It was found that the storage modulus of the PMMA/HDPE blends also related to the HDPE content. The lower storage modulus was observed in the PMMA/HDPE. The storage modulus of the PMMA/HDPE blends contained EMAC tended to decrease with increasing HDPE content, but the blends with 20 %wt of HDPE showed slightly higher value than at 10 %wt of HDPE. The PMMA/HDPE blends exhibited larger storage modulus over the PMMA/HDPE/EMAC blends excepted at 30 and 50 %wt of HDPE. However, both the blends with and without EMAC compatibilizer expressed lower storage modulus compared to pure PMMA. According to the inherent property of HDPE which possessed lesser storage modulus than PMMA so the modulus of the blends should locate between the values of each pure polymer. Therefore, it could be implied that addition of HDPE did not improved the elastic property of the PMMA/HDPE blends even in the presence of EMAC compatibilzer. Figure 50 represents the tan delta of pure PMMA, pure HDPE and PMMA/HDPE blends at different temperature. The tan delta of pure HDPE increased 68 with increasing temperature. Pure PMMA exhibited one apparent peak at the temperature of 110.8oC which referred to the glass transition temperature. The result revealed that one small peak at 112oC was noticed in the PMMA/HDPE 90/10 blends while other PMMA/HDPE and PMMA/HDPE/5phr EMAC blends had no peak. The tan delta of PMMA/HDPE blends tended to decrease when HDPE content increased, but the lowest value found in the blends with 10 %wt of HDPE. Besides, the blends contained 20 to 30 %wt of HDPE gave higher tan delta compared to pure PMMA. The PMMA/HDPE/5phr EMAC blends showed that larger amount of HDPE in the blends led to lesser value of tan delta. The blends contained EMAC displayed higher tan delta than pure PMMA at low HDPE content (10 to 30 %wt). It should be noted that both the blends with and without EMAC compatibilizer exhibited greater value of tan delta than pure HDPE. At low HDPE content, the blends with EMAC gave higher tan delta than the blends without compatiblizer. However, over 30 %wt of HDPE the blends without EMAC showed larger tan delta. This indicated that the increased in HDPE amount promoted the reduction of tan delta of the PMMA/HDPE blends even in the presence of EMAC compatibilizer. The lower tan delta means the polymer was more difficult to deform so the blending PMMA with HDPE could improve the viscoelastic property of the blends. Furthermore, the addition of EMAC had no effect on the melting temperature of the blends compared to the PMMA/HDPE blends as could be seen from the unchanged position of the peak in tan delta curve after glass transition temperature. 5.3.1.5 Thermal Properties (1) DSC analysis Thermal properties of PMMA/HDPE blends with and without EMAC compatibilizer at various ratios of PMMA to HDPE were investigated by DSC technique. The behavior of the PMMA/HDPE and PMMA/HDPE/5phr EMAC blends at different temperature was shown in Figure 51 and 52, respectively. The melting temperature of pure HDPE located at 129.7oC. All the blends showed one melting peak in the heating DSC curve. The position of the peak was gradually shifted to higher temperature and the peak height became larger when increased HDPE content. This result indicated that the addition of HDPE to PMMA referred to the increment of the crystalline part in the PMMA/HDPE blends. Therefore, the obtained blends exhibited higher melting temperature when added higher amount of HDPE. However, EMAC compatibilizer had no effect on the melting temperature of the blends. The variation of percentage crystallinity of HDPE in the blends was compared with that of pure HDPE. The results found that the percentage crystallinity was increased with increasing HDPE content as showed in Table 7. This might be related to the addition of higher HDPE loading referred to the increased in crystalline part in the blends. It is known that HDPE was a semi-crystalline polymer which required larger energy to change from semi-crystalline to a solid amorphous phase than amorphous polymer. Therefore, the increased in melting temperature was observed when added higher HDPE loading was reasonable. The percentage crystallinity of the PMMA/HDPE/5phr EMAC blends slightly higher than the blends without compatibilizer. This may be due to the increment of crystalline part in the blends from ethylene in EMAC molecule. 69 3500000 PMMA PMMA/HDPE 90/10 PMMA/HDPE 80/20 PMMA/HDPE 70/30 3000000 PMMA/HDPE 60/40 PMMA/HDPE 50/50 PMMA/HDPE/EMAC 90/10/5 PMMA/HDPE/EMAC 80/20/5 2500000 PMMA/HDPE/EMAC 70/30/5 PMMA/HDPE/EMAC 60/40/5 PMMA/HDPE/EMAC 50/50/5 HDPE E' (MPa) 2000000 1500000 1000000 500000 0 30 40 50 60 70 80 90 100 110 120 130 140 150 160 Temperature (๐C) Figure 49 Storage modulus of PMMA/HDPE blends with and without EMAC compatibilizer at different composition. 70 40 PMMA PMMA/HDPE 90/10 35 PMMA/HDPE 80/20 PMMA/HDPE 70/30 PMMA/HDPE 60/40 PMMA/HDPE 50/50 30 PMMA/HDPE/EMAC 90/10/5 PMMA/HDPE/EMAC 80/20/5 PMMA/HDPE/EMAC 70/30/5 25 PMMA/HDPE/EMAC 60/40/5 tan delta PMMA/HDPE/EMAC 50/50/5 HDPE 20 15 10 5 0 30 40 50 60 70 80 90 100 110 Temperature (๐C) 120 130 140 150 160 Figure 50 Temperature versus tan delta of PMMA/HDPE blends with and without EMAC compatibilizer. 71 Heat Flow Endo Up (mW) PMMA PMMA/HDPE (90/10)_200C PMMA/HDPE (80/20)_200C PMMA/HDPE (70/30)_200C PMMA/HDPE (60/40)_200C PMMA/HDPE (50/50)_200C HDPE 50 60 Figure 51 70 80 90 100 110 120 130 140 150 160 170 180 190 200 Temperature (๐C) DSC graph of PMMA/HDPE blends at different compositions. Heat Flow Endo Up (mW) PMMA/HDPE/EMAC 90/10/5 PMMA/HDPE/EMAC 80/20/5 PMMA/HDPE/EMAC 70/30/5 PMMA/HDPE/EMAC 60/40/5 PMMA/HDPE/EMAC 50/50/5 HDPE 50 60 Figure 52 compositions. 70 80 90 100 110 120 130 140 150 160 170 180 190 200 Temperature (oC) DSC graph of PMMA/HDPE/5phr EMAC blends at different 72 Table 7 Melting temperature and percentage crystallinity of PMMA/HDPE and PMMA/HDPE/EMAC blends at different composition. Pure HDPE (200oC) PMMA/HDPE (90/10) (200oC) PMMA/HDPE (80/20) (200oC) PMMA/HDPE (70/30) (200oC) PMMA/HDPE (60/40) (200oC) PMMA/HDPE (50/50) (200oC) Melting Temperature (oC) 129.7 127.1 127.8 128.4 128.4 128.8 PMMA/HDPE/EMAC (90/10/5) PMMA/HDPE/EMAC (80/20/5) PMMA/HDPE/EMAC (70/30/5) PMMA/HDPE/EMAC (60/40/5) PMMA/HDPE/EMAC (50/50/5) 126.7 127.1 127.7 127.7 128.6 Sample Crystallinity (%) 46.6 3.6 8.1 12.6 17.0 20.5 5.0 10.0 17.3 23.3 20.3 (2) TGA analysis The thermal stability of the PMMA/HDPE blends with and without EMAC compatibilizer was examined by TGA. The decomposition temperature of each sample was measured and reported in Table 8. The increased in decomposition temperature in every % weight loss was observed in all samples of PMMA/HDPE and PMMA/HDPE/5phr EMAC blends when increased the amount of HDPE. The decomposition temperature of all the blends was higher value than that of pure PMMA but did not larger than pure HDPE. It could be implied that blending PMMA with HDPE resulted in the improvement in the thermal stability of the obtained blends. However, the addition of EMAC compatibilizer had no effect on the decomposition temperature of the PMMA/HDPE blends. 5.3.2 PMMA/HDPE blends with and without EGMA and EMA-GMA compatibilizer 5.3.2.1 Torque measurement The flow characteristic of polymer blends could be observed from the change of mixing torque at different time. It is known that when the polymer is introduced in the mixing chamber, the solid pellets propose a resistance to the motion of rotor so the torque increases. When this resistance is overcome, the torque will gradually decreased and approach a steady-state after a short time. Finally, when the heat transfer is enough to completely melt the particles, the torque decreases and reaches steady-state again [95, 96]. The rheology of PMMA/HDPE blends and the effect of compatibilizer were investigated by recording torque during melt blending step. The mixing torque of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer were measured in an internal mixer. All the polymers and its blends were processed at 170oC with a rotor speed of 50 rpm, and a total mixing time of 15 min. 73 Table 8 Decomposition temperature of PMMA/HDPE and PMMA/HDPE/EMAC blends at different composition. Sample Td5 Td10 Td50 Pure PMMA (200oC) Pure HDPE (200oC) PMMA/HDPE (90/10) (200oC) PMMA/HDPE (80/20) (200oC) PMMA/HDPE (70/30) (200oC) PMMA/HDPE (60/40) (200oC) PMMA/HDPE (50/50) (200oC) 334.4 438.5 338.2 336.2 335.6 335.8 344.4 346.6 451.9 349.2 346.9 346.5 348.0 355.8 374.2 475.9 374.8 372.4 372.4 376.2 421.3 PMMA/HDPE/EMAC (90/10/5) PMMA/HDPE/EMAC (80/20/5) PMMA/HDPE/EMAC (70/30/5) PMMA/HDPE/EMAC (60/40/5) PMMA/HDPE/EMAC (50/50/5) 336.5 331.6 334.8 345.1 352.6 346.3 342.4 347.2 355.4 361.9 370.4 366.2 374.1 393.9 429.9 The melt mixing torque of PMMA/HDPE blends with plotted as a function of time at different composition as shown in Figures 53-57. PMMA showed maximum torque values while the lowest value was observed in HDPE. All the blends expressed lower torque values than PMMA and higher than pure HDPE. Considering the steady torque, at the composition of HDPE content below 20 %wt the mixing torque of the blends contained EMA-GMA and EGMA is larger than the blends without compatibilizer as shown in Table 9. The increasing torque indicated that the polymer blends was more viscous. This may be due to the physical change because the compatibilizers promote the longer chain of PMMA and HDPE or increase the entanglement of polymer chain which resulted in the greater resistance to flow [102104]. In comparison, the addition of EMA-GMA provided higher mixing torque than EGMA. This incident may cause by the structure of EMA-GMA contained higher content of methyl acrylate group which led to better compatibility with PMMA than HDPE and increased the amount of viscous phase in the blends. It could be observed that EGMA was more compatible with HDPE because the major component is ethylene, so the blends with EGMA displayed a little better flow property than that the blends with EMA-GMA. In contrast, at HDPE content larger than 30 %wt the PMMA/HDPE blends exhibited larger torque than the blends with compatibilizer. The high HDPE content allow the polymer blends flow easily, even in the absence of compatibilizer. Because the melt flow index of HDPE was much higher than PMMA, so it induced the PMMA to flow together. Therefore, the lower mixing torque compared to the blends with low HDPE content was observed. Moreover, it could be seen that the addition of compatibilizer could improve the flow property of PMMA/HDPE blends especially at high HDPE amount. Because both EMA-GMA and EGMA contained ethylene group in their molecule so the blends with compatibilizer expressed lower mixing torque than the PMMA/HDPE blends. 74 40 PMMA PMMA/HDPE 90/10 35 PMMA/HDPE/EMA-GMA 90/10/5 30 Torque (N.m) PMMA/HDPE/EGMA 90/10/5 25 HDPE 20 15 10 5 0 0 1 2 3 4 5 6 7 8 9 Time (min) 10 11 12 13 14 15 Figure 53 Torque versus mixing time of PMMA/HDPE (90/10) blends with and without compatibilizer. 40 PMMA 35 PMMA/HDPE 80/20 PMMA/HDPE/EMA-GMA 80/20/5 30 Torque (N.m) PMMA/HDPE/EGMA 80/20/5 25 HDPE 20 15 10 5 0 0 1 2 3 4 5 6 7 8 9 Time (min) 10 11 12 13 14 15 Figure 54 Torque versus mixing time of PMMA/HDPE (80/20) blends with and without compatibilizer. 75 40 PMMA PMMA/HDPE 70/30 35 PMMA/HDPE/EMA-GMA 70/30/5 30 Torque (N.m) PMMA/HDPE/EGMA 70/30/5 25 HDPE 20 15 10 5 0 0 1 2 3 4 5 6 7 8 9 Time (min) 10 11 12 13 14 15 Figure 55 Torque versus mixing time of PMMA/HDPE (70/30) blends with and without compatibilizer. 40 PMMA 35 PMMA/HDPE 60/40 PMMA/HDPE/EMA-GMA 60/40/5 Torque (N.m) 30 PMMA/HDPE/EGMA 60/40/5 HDPE 25 20 15 10 5 0 0 1 2 3 4 5 6 7 8 9 Time (min) 10 11 12 13 14 15 Figure 56 Torque versus mixing time of PMMA/HDPE (60/40) blends with and without compatibilizer. 76 40 PMMA 35 PMMA/HDPE 50/50 Torque (N.m) PMMA/HDPE/EMA-GMA 50/50/5 30 PMMA/HDPE/EGMA 50/50/5 25 HDPE 20 15 10 5 0 0 1 2 3 4 5 6 7 8 9 Time (min) 10 11 12 13 14 15 Figure 57 Torque versus mixing time of PMMA/HDPE (50/50) blends with and without compatibilizer. Table 9 Steady torque of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer at different composition. Sample o Steady torque (N.m) PMMA(170 C) PMMA/HDPE 90/10 PMMA/HDPE 80/20 PMMA/HDPE 70/30 PMMA/HDPE 60/40 PMMA/HDPE 50/50 17.5 12.9 8.2 7.0 6.3 5.6 PMMA/HDPE/EMA-GMA 90/10/5 PMMA/HDPE/EMA-GMA 80/20/5 PMMA/HDPE/EMA-GMA 70/30/5 PMMA/HDPE/EMA-GMA 60/40/5 PMMA/HDPE/EMA-GMA 50/50/5 14.8 12.4 6.6 5.7 4.5 PMMA/HDPE/EGMA 90/10/5 PMMA/HDPE/EGMA 80/20/5 PMMA/HDPE/EGMA 70/30/5 PMMA/HDPE/EGMA 60/40/5 PMMA/HDPE/EGMA 50/50/5 HDPE (170oC) 13.5 9.5 5.3 5.4 4.2 0.4 77 5.3.2.2 Morphology The effects of the compatibilizer types on the morphology and properties of PMMA/HDPE blends were investigated by the addition of the two compatibilizers in the blends. The morphology of PMMA/HDPE blends with EGMA and EMA-GMA were analyzed from SEM images. Figure 58 represents the fracture surfaces of the PMMA/EGMA and HDPE/EGMA blends at different content of EGMA (3 and 5 phr). It was observed that the surface of HDPE/EGMA blends showed one-phase morphology which indicated the miscibility of the two polymers. In contrast, EGMA form as small spherical particle and uniformly dispersed in PMMA matrix. SEM images obviously indicated the preferential location of EGMA in HDPE phase. Figure 59 represents the fracture surfaces of PMMA/HDPE blends with 3 phr of EGMA at different ratios of PMMA to HDPE. The morphology revealed that PMMA was the matrix phase with dispersed HDPE phase. At 10 %wt of HDPE the dispersed phase particles were quite spherical and uniform. HDPE phase was more continuous and the fracture surface became more stretch when HDPE content larger than 20 %wt as shown in Figure 59(c) to 59(f). The PMMA/HDPE blends contained 5 phr of EGMA were also examined by SEM as shown in Figure 60. The morphology of these blends was similar to the PMMA/HDPE blends with EGMA 3 phr. However, the phase continuity at high content of HDPE did not obvious as in the blends with 3 phr of EGMA. The morphology of the PMMA and HDPE blends with 3 and 5 phr of EMA-GMA were also examined by SEM technique. The fracture surface of each blend was compared with that of pure PMMA and pure HDPE, as shown in Figure 61. Both the blends contained 3 and 5 phr of EMA-GMA showed analogous morphology that the spherical EMA-GMA particles were dispersed in HDPE matrix. However, some of these dispersed particles were covered with the stretched HDPE phase. This incident may be occurred during melt blending step because of the ductility property of HDPE. The blends of PMMA with EMA-GMA also investigated. In contrast, PMMA blends with 3 phr of EMA-GMA exhibited nearly smooth surface as pure PMMA. When EMA-GMA content increased to 5 phr the fracture surface became rougher but phase separation did not observe. The blends morphology could confirm that EMA-GMA preferred to locate in PMMA phase. This may be due to EMA-GMA contained methyl acrylate group in its molecule so it was more compatible with PMMA than with HDPE phase. SEM micrographs in Figure 62 represent the impact fracture surfaces of PMMA/HDPE blends with 3 phr of EMA-GMA. At 10% wt of HDPE, the blends exhibited the morphology of dispersed and matrix phase. The nearly sphere HDPE particles spread in PMMA matrix phase. The dispersed HDPE particles became more continuous at higher HDPE content than 20 %wt. In the blends with 5 phr of EMAGMA, the fracture surfaces were analogous to the blends contained 3 phr of EMAGMA as shown in Figure 63. The evident effect of compatibilizer content was not observed because it is used in small quantities. However, the continuous morphology of HDPE phase occurred quite slower. The results indicated that the addition of EMAGMA compatibilizer has low efficiency to improve the compatibility between PMMA and HDPE. 78 10 μm 10 μm (a) Pure PMMA (b) Pure HDPE 10 μm 10 μm (d) HDPE/3phr EGMA (c) PMMA/3phr EGMA 10 μm (e) PMMA/5phr EGMA Figure 58 10 μm (f) HDPE/5phr EGMA SEM micrographs of PMMA/EGMA and HDPE/EGMA blends. 79 20 μm (b) PMMA/HDPE/EGMA 90/10/3 (a) Pure PMMA 20 μm (c) PMMA/HDPE/EGMA 80/20/3 20 μm (e) PMMA/HDPE/EGMA 60/40/3 Figure 59 20 μm 20 μm (d) PMMA/HDPE/EGMA 70/30/3 20 μm (f) PMMA/HDPE/EGMA 50/50/3 SEM micrographs of PMMA/HDPE (w/w) blends with 3 phr of EGMA. 80 20 μm (a) Pure PMMA (b) PMMA/HDPE/EGMA 90/10/5 20 μm (c) PMMA/HDPE/EGMA 80/20/5 20 μm (e) PMMA/HDPE/EGMA 60/40/5 Figure 60 20 μm 20 μm (d) PMMA/HDPE/EGMA 70/30/5 20 μm (f) PMMA/HDPE/EGMA 50/50/5 SEM micrographs of PMMA/HDPE (w/w) blends with 5 phr of EGMA. 81 10 μm (a) Pure PMMA (b) Pure HDPE 10 μm (c) PMMA/3phr EMA-GMA 10 μm (e) PMMA/5phr EMA-GMA Figure 61 blends. 10 μm 10 μm (d) HDPE/3phr EMA-GMA 10 μm (f) HDPE/5phr EMA-GMA SEM micrographs of PMMA/EMA-GMA and HDPE/EMA-GMA 82 20 μm (a) Pure PMMA (b) PMMA/HDPE/EMA-GMA 90/10/3 20 μm (c) PMMA/HDPE/EMA-GMA 80/20/3 20 μm (e) PMMA/HDPE/EMA-GMA 60/40/3 Figure 62 EMA-GMA. 20 μm 20 μm (d) PMMA/HDPE/EMA-GMA 70/30/3 20 μm (f) PMMA/HDPE/EMA-GMA 50/50/3 SEM micrographs of PMMA/HDPE (w/w) blends with 3phr of 83 20 μm (b) PMMA/HDPE/EMA-GMA 90/10/5 (a) Pure PMMA 20 μm (c) PMMA/HDPE/EMA-GMA 80/20/5 20 μm (e) PMMA/HDPE/EMA-GMA 60/40/5 Figure 63 EMA-GMA. 20 μm 20 μm (d) PMMA/HDPE/EMA-GMA 70/30/5 20 μm (f) PMMA/HDPE/EMA-GMA 50/50/5 SEM micrographs of PMMA/HDPE (w/w) blends with 5phr of 84 5.3.2.3 Mechanical properties (1) Impact property The Izod impact strength of PMMA/HDPE blends with and without compatibilizers was plotted versus HDPE content as shown in Figure 64. The results found that the impact strength of PMMA/HDPE blends tended to decrease when increased amount of HDPE. Besides, all the PMMA/HDPE blends showed lower impact strength than pure PMMA. This result was in agreement with the blends morphology that the poor adhesion between PMMA and HDPE phases was more evident when increased HDPE content. The impact strength of the blends with both compatibilizers also decreased with increasing HDPE content. At low HDPE content (10 to 20 %wt), the PMMA/HDPE/5phr EGMA showed larger value of impact strength than the PMMA/HDPE and PMMA/HDPE/EMA-GMA blends. After this composition, the blends without compatibilizer exhibited greater impact strength. At HDPE content higher than 20 %wt, the PMMA/HDPE blends showed higher impact strength than the blends with EGMA and EMA-GMA. However, the blends contained EGMA provided larger impact strength than EMA-GMA. The effect of compatibilizer content on the impact property of the blends with EMA-GMA and EGMA exhibited in similar trend. At the composition of 10 and 20 %wt of HDPE, the addition of 5 phr compatibilizer gave higher impact strength. After these two compositions, the blends with 3 phr of compatibilizer showed larger value of impact strength. This may be inferred that at high HDPE amount the stable morphology of the blends did not achieve even in the presence of EMA-GMA and EGMA compatibilizer. 30 PMMA/HDPE (170C) PMMA/HDPE/3phr EMA-GMA 25 Impact strength (mJ/mm2) PMMA/HDPE/5phr EMA-GMA PMMA/HDPE/3phr EGMA 20 PMMA/HDPE/5phr EGMA 15 10 5 0 0 10 20 30 HDPE content (%wt) 40 50 Figure 64 Impact strength of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer at different composition. 85 (2) Tensile properties Young’s modulus The Young’s modulus of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer at different composition was shown in Figure 65. Both the PMMA/HDPE blends with and without compatibilizer showed similar trend that the Young’s modulus gradually decreased with increasing HDPE amount. At low HDPE content, the blends contained 3 phr of compatibilizers showed slightly higher Young’s modulus than PMMA/HDPE blends. At HDPE amount higher than 20 %wt the blends without compatibilizers exhibited greater value of Young’s modulus. The compatibilizer content had small effect on the property of the blends. The blends with 3 phr of EMA-GMA and EGMA provided better Young’s modulus than 5 phr throughout composition range. 1800 PMMA/HDPE (170C) 1600 PMMA/HDPE/3phr EMA-GMA Young's modulus (MPa) PMMA/HDPE/5phr EMA-GMA 1400 PMMA/HDPE/3phr EGMA PMMA/HDPE/5phr EGMA 1200 1000 800 600 400 200 0 0 10 20 30 HDPE content (%wt) 40 50 Figure 65 Young’s modulus of PMMA/HDPE blends with and without EMAGMA and EGMA compatibilizer at different composition. Tensile strength The tensile strength of the PMMA/HDPE blends with and without compatibilizer at different HDPE content was shown in Figure 66. The PMMA/HDPE blends showed the decreased in the tensile strength when increased HDPE amount but at small amount of HDPE the value was higher than pure PMMA. The tensile strength of PMMA/HDPE blends with compatibilizer decreased with increasing HDPE content. At low HDPE content, the tensile strength of the PMMA/HDPE blends was greater than the blends with compatibilizer. In comparison, the addition of EGMA 86 compatibilizer provided larger tensile strength than EMA-GMA at low HDPE content. The results indicated that HDPE did not enhance the tensile strength of the PMMA/HDPE blends. However, the addition of compatibilizer could slightly improve the tensile strength of the blends at high HDPE content. 80 PMMA/HDPE (170C) PMMA/HDPE/3phr EMA-GMA 70 Tensile strength (MPa) PMMA/HDPE/5phr EMA-GMA 60 PMMA/HDPE/3phr EGMA PMMA/HDPE/5phr EGMA 50 40 30 20 10 0 0 10 20 30 HDPE content (%wt) 40 50 Figure 66 Tensile strength of PMMA/HDPE blends with and without EMAGMA and EGMA compatibilizer at different composition. Stress at break Figure 67 represents the stress at break of PMMA/HDPE blends with and without compatibilizer at various ratios of PMMA to HDPE. The results found that the stress at break of PMMA/HDPE blends decreased as HDPE content increased. At low HDPE content, the PMMA/HDPE blends showed higher stress at break than the blends with compatibilizers. However, the blends with EMA-GMA and EGMA compatibilizer exhibited larger value of stress at break than PMMA/HDPE blends at high HDPE content. Moreover, the blends with EGMA compatibilizer expressed greater stress at break than the blends with EMA-GMA at low HDPE content. The effect of compatibilizer amount was also examined. The blends contained 3 phr of both compatibilizer seem to be more effective than 5 phr. This indicated that the incorporation of EMA-GMA and EGMA could slightly improve the property of the blends at high HDPE content. 87 80 PMMA/HDPE (170C) PMMA/HDPE/3phr EMA-GMA 70 PMMA/HDPE/5phr EMA-GMA Stress at break (MPa) 60 PMMA/HDPE/3phr EGMA PMMA/HDPE/5phr EGMA 50 40 30 20 10 0 0 10 20 30 HDPE content (%wt) 40 50 Figure 67 Stress at break of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer at different composition. Percentage strain at break The percentage strain at break of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer at different content is shown in Figure 68. The PMMA/HDPE blends expressed lower percentage strain at break when increased amount of HDPE. The PMMA/HDPE blends contained EMA-GMA and EGMA compatibilizer also showed the reduction in the percentage strain at break throughout the composition range. The addition of 3 phr of EGMA compatibilizer gave higher value of percentage strain at break than the PMMA/HDPE blends in every composition. At higher HDPE content than 30 %wt the blends with both compatibilizers showed larger percentage strain at break than the PMMA/HDPE blends. In comparison, the blends with EGMA gave higher value of percentage strain at break than EMA-GMA at low HDPE content while EMA-GMA showed larger value at high HDPE content. Moreover, the incorporation of 3 phr of compatibilizer seems to be more effective than 5 phr. 88 20 PMMA/HDPE (170C) Percentage strain at break PMMA/HDPE/3phr EMA-GMA PMMA/HDPE/5phr EMA-GMA 15 PMMA/HDPE/3phr EGMA PMMA/HDPE/5phr EGMA 10 5 0 0 10 20 30 HDPE content (%wt) 40 50 Figure 68 Percentage strain at break of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer at different composition. 5.3.2.4 Thermomechanical property The effect of the incorporation of other two compatibilizers, EMAGMA and EGMA, on the viscoelastic property of PMMA/HDPE blends was also examined. The variation of storage modulus of PMMA/HDPE blends with 3 and 5 phr of EMA-GMA were represented in Figure 69. The storage modulus of pure PMMA tended to decrease with increasing temperature and the sharply decreased was noticed at higher temperature than 80oC. The PMMA/HDPE blends revealed that at HDPE content below 30 %wt, the storage modulus increased as HDPE amount increased. After these compositions the blends with lower HDPE showed larger storage modulus. The reduction of storage modulus when added higher amount of HDPE was occurred due to the increased in amount of soft rubber phase in the blends, which indicated the decreased in material rigidity [13, 92]. This means that blending with HDPE could improve the viscoelastic property at small amount of HDPE. The reduction of the storage modulus when increased amount of HDPE was also observed in the PMMA/HDPE blends containing both 3 and 5 phr of EMA-GMA. It could be seen that the storage modulus of PMMA/HDPE blends was higher than the blends with EMA-GMA except at 10 %wt of HDPE. The effect of compatibilizer content was also investigated. The blends with 3 phr of EMA-GMA gave higher value of storage modulus than the blends with 5 phr when compared at the same composition. This may be inferred that the viscoelastic property of the PMMA/HDPE blends could be enhanced by the addition of HDPE. However, EMA-GMA compatibilizer did not 89 improved the viscoelastic property of the blends and the compatibilizer content had only slightly effect on the property of the blends. In addition, the tan delta which referred to the ratio of loss modulus to storage modulus was also studied. Figure 70 represents the variation of tan delta of the PMMA/HDPE blends with and without EMA-GMA compatibilizer at different content. It was known that the glass transition temperature of the polymer can be determined from the peak of tan delta curve [14]. The results revealed that the glass transition temperature of PMMA located at 114.4oC. It could be clearly seen that all the blends exhibited one apparent peak in tan delta curve. Moreover, the tan delta of the PMMA/HDPE blends decreased with increasing HDPE content but the blends with 20 %wt of HDPE showed slightly higher than the blends with 10 %wt of HDPE. The PMMA/HDPE/EMA-GMA blends also showed a similar trend to the PMMA/HDPE blends that the tan delta became lower when increased HDPE content. The blends contained EMA-GMA expressed slightly larger tan delta value compare to the blends without compatibilizer, except at 30 and 50 %wt of HDPE. It could be seen that the position of the peak in tan delta curve of the PMMA/HDPE and PMMA/HDPE/EMA-GMA blends did not change with HDPE content, so the addition of HDPE and EMA-GMA had no effect on the glass transition temperature of the blends. Figure 71 represents the storage modulus of PMMA/HDPE blends with and without EGMA compatibilizer at different composition. The results revealed that at HDPE content below 30 %wt, the storage modulus of PMMA/HDPE increased as HDPE amount increased. After these compositions the blends with lower HDPE showed larger storage modulus. The PMMA/HDPE blends with EGMA 5 phr showed a decreased in the value of storage modulus with increasing HDPE content. However, the storage modulus of PMMA/HDPE blends still higher than the blends with EGMA compatibilizer. The tan delta of PMMA/HDPE blends with and without EGMA compatibilizer at different composition was plotted in Figure 72. It could be seen that at low HDPE content, the blends without EGMA express larger value of tan delta. The PMMA/HDPE/EGMA blend showed lower tan delta when increased HDPE content. Moreover, blending with 3 phr of EGMA provided greater value of tan delta in every composition except at 40 %wt of HDPE so the addition of 5 phr seem to be more effective. This result indicated that the incorporation of EGMA compatibilizer did not improved the viscoelastic property of the PMMA/HDPE blends. Furthermore, the addition of EGMA compatibilizer had no effect on the glass transition temperature of the blends as could be seen from the same position of tan delta peak at different HDPE content. According to the obtained results, the addition of HDPE did not improve the viscoelastic property of the PMMA/HDPE blend. Moreover, the addition of EMA-GMA and EGMA showed similar effect that it did not enhance the viscoelastic property of the blends. Besides, EMA-GMA and EGMA had no effect on the glass transition temperature of the blends as could be seen from the very slightly change in the position of tan delta peak. The compatibilizer content had slightly effect on the thermomechanical property of the PMMA/HDPE blends. The optimum compatibilizer content for EMAC and EMA-GMA is 5 phr and for EGMA the suitable content is 3 phr. 90 4500000 PMMA PMMA/HDPE 90/10 PMMA/HDPE 80/20 4000000 PMMA/HDPE 70/30 PMMA/HDPE 60/40 PMMA/HDPE 50/50 3500000 PMMA/HDPE/EMA-GMA 90/10/3 PMMA/HDPE/EMA-GMA 80/20/3 PMMA/HDPE/EMA-GMA 70/30/3 3000000 PMMA/HDPE/EMA-GMA 60/40/3 E' (MPa) PMMA/HDPE/EMA-GMA 50/50/3 PMMA/HDPE/EMA-GMA 90/10/5 2500000 PMMA/HDPE/EMA-GMA 80/20/5 PMMA/HDPE/EMA-GMA 70/30/5 PMMA/HDPE/EMA-GMA 60/40/5 2000000 PMMA/HDPE/EMA-GMA 50/50/5 HDPE 1500000 1000000 500000 0 30 40 50 60 70 80 90 100 110 120 130 140 150 160 Temperature (๐C) Figure 69 Storage modulus of PMMA/HDPE blends with and without EMAGMA compatibilizer at different composition. 91 0.7 PMMA PMMA/HDPE 90/10 PMMA/HDPE 80/20 PMMA/HDPE 70/30 0.6 PMMA/HDPE 60/40 PMMA/HDPE 50/50 PMMA/HDPE/EMA-GMA 90/10/3 PMMA/HDPE/EMA-GMA 80/20/3 0.5 PMMA/HDPE/EMA-GMA 70/30/3 PMMA/HDPE/EMA-GMA 60/40/3 PMMA/HDPE/EMA-GMA 50/50/3 PMMA/HDPE/EMA-GMA 90/10/5 0.4 tan delta PMMA/HDPE/EMA-GMA 80/20/5 PMMA/HDPE/EMA-GMA 70/30/5 PMMA/HDPE/EMA-GMA 60/40/5 PMMA/HDPE/EMA-GMA 50/50/5 0.3 HDPE 0.2 0.1 0 30 40 50 60 70 80 90 100 110 Temperature (oC) 120 130 140 150 160 Figure 70 Temperature versus tan delta of PMMA/HDPE blends with and without EMA-GMA compatibilizer at different composition. 92 4500000 PMMA PMMA/HDPE 90/10 PMMA/HDPE 80/20 4000000 PMMA/HDPE 70/30 PMMA/HDPE 60/40 PMMA/HDPE 50/50 3500000 PMMA/HDPE/EGMA 90/10/3 PMMA/HDPE/EGMA 80/20/3 3000000 PMMA/HDPE/EGMA 70/30/3 PMMA/HDPE/EGMA 60/40/3 E' (MPa) PMMA/HDPE/EGMA 50/50/3 2500000 PMMA/HDPE/EGMA 90/10/5 PMMA/HDPE/EGMA 80/20/5 PMMA/HDPE/EGMA 70/30/5 2000000 PMMA/HDPE/EGMA 60/40/5 PMMA/HDPE/EGMA 50/50/5 1500000 HDPE 1000000 500000 0 30 40 50 60 70 80 90 100 110 120 130 140 150 160 Temperature (๐C) Figure 71 Storage modulus of PMMA/HDPE blends with and without EGMA compatibilizer at different composition. 93 0.7 PMMA PMMA/HDPE 90/10 PMMA/HDPE 80/20 PMMA/HDPE 70/30 0.6 PMMA/HDPE 60/40 PMMA/HDPE 50/50 PMMA/HDPE/EGMA 90/10/3 0.5 PMMA/HDPE/EGMA 80/20/3 PMMA/HDPE/EGMA 70/30/3 PMMA/HDPE/EGMA 60/40/3 PMMA/HDPE/EGMA 50/50/3 0.4 tan delta PMMA/HDPE/EGMA 90/10/5 PMMA/HDPE/EGMA 80/20/5 PMMA/HDPE/EGMA 70/30/5 PMMA/HDPE/EGMA 60/40/5 0.3 PMMA/HDPE/EGMA 50/50/5 HDPE 0.2 0.1 0 30 40 50 60 70 80 90 100 110 Temperature (oC) 120 130 140 150 160 Figure 72 Temperature versus tan delta of PMMA/HDPE blends with and without EGMA compatibilizer at different composition. 94 5.2.3.5 Thermal property (1) DSC analysis The thermal properties of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer at various ratios of PMMA to HDPE were examined by DSC technique. The thermal behavior of the PMMA/HDPE blends at different temperature was shown in Figure 73. The blends showed one melting peak in the heating DSC curve. The results found that the position of the peak was shifted to higher temperature when increased HDPE content. The increased of HDPE amount referred to the increment of crystalline part in the PMMA/HDPE blends which resulted in the higher melting temperature. The melting temperature of PMMA/HDPE blends contained EMA-GMA and EGMA showed the similar trend to the PMMA/HDPE blends that as could be seen from Figures 74 to 77. However, the incorporation of both compatibilizers had no effect on the melting temperature of the blends. The variation of percentage crystallinity of HDPE in the blends at different composition was compared with pure HDPE. The results revealed that the percentage crystallinity of the blends increased with increasing HDPE content as shown in Table 10. This incident was the consequence of higher crystalline part in the blends when added larger amount of HDPE. The blends contained EMA-GMA and EGMA expressed higher percentage crystallinity than the blends without compatibilizer. Because both EMA-GMA and EGMA consisted of ethylene, so the incorporation of compatibilizer increased the crystalline part of the blends. Heat Flow Endo Up (mW) PMMA/HDPE(90/10)_170C PMMA/HDPE(80/20)_170C PMMA/HDPE(70/30)_170C PMMA/HDPE(60/40)_170C PMMA/HDPE(50/50)_170C 50 Figure 73 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 Temperature (๐C) DSC graph of PMMA/HDPE blends at different compositions. 95 Heat Flow Endo Up (mW) PMMA/HDPE/EMA-GMA(90/10/3) PMMA/HDPE/EMA-GMA(80/20/3) PMMA/HDPE/EMA-GMA(70/30/3) PMMA/HDPE/EMA-GMA(60/40/3) PMMA/HDPE/EMA-GMA(50/50/3) 50 60 70 Figure 74 compositions. 80 90 100 110 120 130 140 150 160 170 180 190 200 Temperature (๐C) DSC graph of PMMA/HDPE/3phr EMA-GMA blends at different Heat Flow Endo Up (mW) PMMA/HDPE/EMA-GMA(90/10/5) PMMA/HDPE/EMA-GMA(80/20/5) PMMA/HDPE/EMA-GMA(70/30/5) PMMA/HDPE/EMA-GMA(60/40/5) PMMA/HDPE/EMA-GMA(50/50/5) 50 60 Figure 75 composition. 70 80 90 100 110 120 130 140 150 160 170 180 190 200 Temperature (๐C) DSC graph of PMMA/HDPE/5phr EMA-GMA blends at different 96 Heat Flow Endo Up (mW) PMMA/HDPE/EGMA(90/10/3) PMMA/HDPE/EGMA(80/20/3) PMMA/HDPE/EGMA(70/30/3) PMMA/HDPE/EGMA(60/40/3) PMMA/HDPE/EGMA(50/50/3) 50 60 70 Figure 76 composition. 80 90 100 110 120 130 140 150 160 170 180 190 200 Temperature (๐C) DSC graph of PMMA/HDPE/3phr EGMA blends at different Heat Flow Endo Up (mW) PMMA/HDPE/EGMA(90/10/5) PMMA/HDPE/EGMA(80/20/5) PMMA/HDPE/EGMA(70/30/5) PMMA/HDPE/EGMA(60/40/5) PMMA/HDPE/EGMA(50/50/5) 50 60 Figure 77 composition. 70 80 90 100 110 120 130 140 150 160 170 180 190 200 Temperature (๐C) DSC graph of PMMA/HDPE/5phr EGMA blends at different 97 Table 10 Melting temperature and percentage crystallinity of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer. Sample Pure HDPE (170oC) PMMA/HDPE (90/10) (170oC) PMMA/HDPE (80/20) (170oC) PMMA/HDPE (70/30) (170oC) PMMA/HDPE (60/40) (170oC) PMMA/HDPE (50/50) (170oC) Melting Temperature (oC) 129.7 127.6 127.9 129.2 128.7 128.4 Crystallinity (%) 46.6 3.2 7.1 9.8 14.9 18.8 PMMA/HDPE/EMA-GMA (90/10/3) PMMA/HDPE/EMA-GMA (80/20/3) PMMA/HDPE/EMA-GMA (70/30/3) PMMA/HDPE/EMA-GMA (60/40/3) PMMA/HDPE/EMA-GMA (50/50/3) 127.6 128.0 127.8 128.8 128.9 4.0 5.7 9.1 15.9 19.1 PMMA/HDPE/EMA-GMA (90/10/5) PMMA/HDPE/EMA-GMA (80/20/5) PMMA/HDPE/EMA-GMA (70/30/5) PMMA/HDPE/EMA-GMA (60/40/5) PMMA/HDPE/EMA-GMA (50/50/5) 127.0 127.8 128.3 129.1 128.9 4.9 5.3 12.4 16.3 21.0 PMMA/HDPE/EGMA (90/10/3) PMMA/HDPE/EGMA (80/20/3) PMMA/HDPE/EGMA (70/30/3) PMMA/HDPE/EGMA (60/40/3) PMMA/HDPE/EGMA (50/50/3) 127.1 127.4 127.9 128.2 129.1 3.7 6.8 12.0 16.7 21.6 PMMA/HDPE/EGMA (90/10/5) PMMA/HDPE/EGMA (80/20/5) PMMA/HDPE/EGMA (70/30/5) PMMA/HDPE/EGMA (60/40/5) PMMA/HDPE/EGMA (50/50/5) 127.1 127.4 127.9 127.9 128.6 2.7 6.1 12.7 16.5 19.7 (2) TGA analysis The thermal stability of the PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer was investigated by TGA. The decomposition temperature of the PMMA/HDPE blends with and without compatibilizer tended to increase with increasing HDPE content as could be seen from Table 11. The higher decomposition temperature was noticed when added larger amount of HDPE but the values were still lower than that of pure HDPE, although they were higher than that of pure PMMA. This indicated that HDPE could improve the thermal stability of the 98 PMMA/HDPE blends. However, the compatibilizer types and compatibilizer content had no effect on the thermal behavior of the blends. Therefore, it could be inferred that the incorporation of the three compatibilizers did not improve the thermal stability of PMMA/HDPE blends in the whole range of composition [12]. This may be due to the thermal characteristic of each copolymer that possessed low melting temperature. Table 11 Decomposition temperature of PMMA/HDPE blends with and without EMA-GMA and EGMA compatibilizer. Sample Td5 Td10 Td50 Pure PMMA (170oC) Pure HDPE (170oC) 338.3 448.1 348.3 458.9 373.9 477.8 PMMA/HDPE (90/10) (170oC) PMMA/HDPE (80/20) (170oC) PMMA/HDPE (70/30) (170oC) PMMA/HDPE (60/40) (170oC) PMMA/HDPE (50/50) (170oC) 339.0 341.5 343.3 341.6 349.0 349.6 351.5 353.3 353.3 360.3 376.9 380.1 384.6 387.7 423.6 PMMA/HDPE/EGMA (90/10/3) PMMA/HDPE/EGMA (80/20/3) PMMA/HDPE/EGMA (70/30/3) PMMA/HDPE/EGMA (60/40/3) PMMA/HDPE/EGMA (50/50/3) 340.6 340.3 342.4 342.4 346.6 351.3 350.5 354.3 353.8 358.1 379.6 380.7 387.6 388.3 421.1 PMMA/HDPE/EGMA (90/10/5) PMMA/HDPE/EGMA (80/20/5) PMMA/HDPE/EGMA (70/30/5) PMMA/HDPE/EGMA (60/40/5) PMMA/HDPE/EGMA (50/50/5) 341.8 339.3 343.4 345.1 342.4 352.4 349.5 354.9 356.9 354.3 381.5 378.1 388.0 396.3 393.5 PMMA/HDPE/EMA-GMA (90/10/3) PMMA/HDPE/EMA-GMA (80/20/3) PMMA/HDPE/EMA-GMA (70/30/3) PMMA/HDPE/EMA-GMA (60/40/3) PMMA/HDPE/EMA-GMA (50/50/3) 340.9 338.3 341.3 342.4 349.9 352.2 349.8 353.1 353.5 360.6 382.0 380.1 385.0 389.1 415.7 PMMA/HDPE/EMA-GMA (90/10/5) PMMA/HDPE/EMA-GMA (80/20/5) PMMA/HDPE/EMA-GMA (70/30/5) PMMA/HDPE/EMA-GMA (60/40/5) PMMA/HDPE/EMA-GMA (50/50/5) 341.2 338.9 341.1 342.3 349.2 352.8 349.9 352.8 354.5 360.7 384.2 381.0 387.9 394.8 436.3 CHAPTER 6 CONCLUSIONS 1. PMMA/ABS blends The morphology study revealed that PMMA and ABS were miscible throughout composition range. The value of impact strength, tensile strength, and stress at break of the PMMA/ABS blends increased with increasing ABS content (40 to 90 %wt) while the Young’s modulus and stiffness tended to decrease when added higher amount of ABS. The addition of low ABS content could improve the storage modulus of the blends. This may be due to the good compatibility between two polymer phases so the synergistic property was achieved. All the PMMA/ABS blends exhibited single Tg because the two polymers has similar Tg. The addition of ABS could improve the thermal stability of PMMA/ABS blends which confirmed by the higher decomposition temperature in all compositions. 2. PMMA/copolymer blends The blends morphology indicated that PMMA was good compatibility with a small amount of EMAC and EOC which resulted in the better impact strength. Blending PMMA with both copolymers did not improve the thermomechanical properties of the blends. The addition of EMAC and EOC increased the Tg of the blends but the type of copolymer and copolymer content had no effect on the Tg. The thermal stability of PMMA/EMAC and PMMA/EOC blends was enhanced when increased copolymer content as could be seen from higher decomposition temperature. 3. PMMA/HDPE blends with and without compatibilizer The blends between PMMA and HDPE expressed immiscible morphology. The incompatibility between the two polymers was more evident when increased HDPE content. The addition of HDPE into PMMA did not improve the mechanical and thermomechanical properties of the blends. The melting temperature and percentage crystallinity of the PMMA/HDPE blends increased when increased HDPE content. The decomposition temperature of PMMA/HDPE blends increased as HDPE amount increased indicated that thermal stability of the blends was enhanced. 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APPENDIX APPENDIX A NOMENCLATURE 109 NOMENCLATURE Abbreviations ABS DMA DSC DTA d5 d10 d50 EAA EB EBC ECs EEA EGMA EMAC EMA-GMA EMA-Na EMA-Zn EnBACO-MAH EOC EPDM EPDM-g-MAH EPM FTIR HDAA HDPE LDPE LPE MAH MBS MDI MMA-GMA MMA-MAH mEOC mEPR mEPR-g-MAH mPE mPE-g-MAH OBC OMM PA6 PA66 PANIDBSA PB-g-MAH PBO Acrylonitrile butadiene styrene Dynamic mechanical analysis Differential scanning calorimetry Differential thermal analysis Decomposition temperature of 5% weight loss Decomposition temperature of 10% weight loss Decomposition temperature of 50% weight loss Ethylene-co-acrylic acid Poly(ethylene-co-1-butene) Ethylene-D-butene copolymers Ethylene-D-olefin copolymers Ethylene-ethyl acrylate copolymer Poly(ethylene-co-glycidyl methacrylate) Ethylene-methyl acrylate copolymer Poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) Ethylene-methacrylic copolymer ionized with Na cation Ethylene-methacrylic copolymer ionized with Zn cation Ethylene-n-butyl acrylate-maleic anhydride Ethylene octene copolymer Ethylene-propylene diene copolymer Ethylene-propylene diene copolymer-graft-maleic anhydride Ethylene-propene random copolymer Fourier transforms infrared spectroscopy High density polyethylene modified with acrylic acid High density polyethylene Low density polyethylene Linear polyethylene Maleic anhydride Methyl methacrylate-styrene-butadiene copolymer 4,4’-methylenedi(phenyl isocyanate) Poly(methacrylate-co-glycidyl methacrylate) Poly(methyl methacrylate)-co-maleic anhydride Maleated ethylene octene copolymer Metallocene ethylene-propylene Metallocene ethylene-propylene copolymer Metallocene polyethylene Metallocene polyethylene-graft-maleic anhydride Ethylene-octene block copolymer Organically modified montmorillonite Polyamide 6 Polyamide 6,6 n-dodecyl-benzene sulfonate doped polyaniline Polybutadiene-graft- maleic anhydride 2,2’-(1,3-phenylene)-bis(2-oxazoline) 110 PBT PC PE PEA PEE PEG PE-g-AA PE-g-MAH PET PMMA POM PP PP-cp PP-g-MAH PP-g-SAN PPS PS PS-co-GMA PTT RHDPE RPET SALS SAN SB SBC SBS SBS-g-DEM SBS-g-HEMA SEBS SEbS-g-MAH SEI SEM SEPS SiO2 sPS sPS-g-MAH TEM TGA VLDPE Poly(butylene terepthalate) Polycarbonate Polyethylene Poly(ethylene acrylic acid) Polyethylene elastomer Polyethylene glycol Polyethylene-graft-acrylic acid Polyethylene-graft-maleic anhydride Poly(ethylene terepthalate) Poly(methyl methacrylate) Polyoxymethylene Polypropylene Polypropylene copolymer Polypropylene-graft-maleic anhydride Polypropylene-graft-poly(styrene-co-acrylonitrile) Poly(phenylene sulfide) Polystyrene Polystyrene-co-glycidyl methacrylate Poly(trimethylene terepthalate) Recycled high density polyethylene Recycled poly(ethylene terepthalate) Small-angle light scattering Poly(styrene-co-acrylonitrile) Styrene-butadiene block copolymer Styrene block copolymer Styrene-butadiene-styrene block copolymer Diethyl maleated styrene-butadiene-styrene block copolymer 2-hydroxyethyl methacrylate styrene-butadiene-styrene block copolymer Styrene-(ethylene-butadiene)-styrene triblock copolymer Polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymer-graft-maleic anhydride Scanning electron image Scanning electron microscopy Styrene-ethylene-propylene-styrene triblock copolymer Silicon dioxide (Silica) Syndiotactic polystyrene Syndiotactic polystyrene-graft- maleic anhydride Transmission electron microscopy Thermogravimetric analysis Very low density polyethylene APPENDIX B INTERNATIONAL PROCEEDING 112 International Proceeding Janyaporn Boromtongchoom and Sirirat Wacharawichanant, “Effects of ethylene copolymers on mechanical and morphological properties of poly(methyl methacrylate)/ethylene copolymer blends,” Pure and Applied Chemistry International Conference 2012 (PACCON 2012), Chiang Mai, Thailand, 11-13 Jan, 2012 (Poster presentation) Janyaporn Boromtongchoom and Sirirat Wacharawichanant, “Mechanical and morphological properties of poly(methyl methacrylate)/high density polyethylene blends with ethylene-methyl acrylate copolymer,” 2nd TIChE International Conference 2012, Nakhonratchasima, Thailand, 25-26 Oct, 2012 (Oral presentation) 113 Biography Name-Family name Birth Address Education 2007 2010 2012 Ms Janyaporn Boromtongchoom 8th Jan 1989 in Nakhon Pathom, Thailand 63 M.9 Taladjinda Sampran Nakhon Pathom, Thailand, 73000. Tel. 084-0190131 High school certificate from Rachinee Burana School Received the degree of the Bachelor of Engineering (Chemical Engineering), Faculty of Engineering and Industrial Technology, Silpakorn University, Nakhon Pathom, Thailand. Further studied in the degree of the master of Chemical Engineering at graduate school, Faculty of Engineering and Industrial Technology, Graduate School, Silpakorn University, Thailand.

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