Jute composite and its applications S. Das Indian Jute Industries’ Research Association 17 Taratola Road, Kolkata-700088, India 1 Background: Composite materials from man-made fibres (i.e. glass fibre, carbon fibre etc.) are already available as products for consumer and industrial uses. A relatively newer concept is to consider natural fibres as a reinforcing material. Stringent environmental legislation and consumer awareness has forced industries to support long term sustainable growth and develop new technology based on renewable feedstock that are independent of fossil fuels. As the current status quo, the main reinforcement for the composite industry is glass fibres; 22.3 million tons (metric) are produced globally on an annual basis. Although glass fibre products have somewhat superior mechanical properties, their life cycle performance is very questionable. Manufacturing of these products not only consume huge energy but their disposal at the end of their life cycle is also very difficult since there is virtually no recycling option. Annual industrial crops grown for fibre, have the potential to supply enough renewable biomass for various bio-products including composites. The scope of possible uses of natural fibres is enormous. This is substantiated by the declaration of United Nation for 2009 as International Year of Natural Fibres (IYNF). All over the world, the bio-composite industry is developing at a significant pace to meet growing consumer awareness and follow new environmental regulations. A survey done by Canadian Agri-Food Research Council (CARC) in 2003 showed that the European automotive industry has already taken the lead and uses approximately 22,000 tons of natural plant fibre in low stress applications in cars. In 2005, 19000 tones of natural fibres were used in Germany for automotive composite. Lignocellulosic bio-fibre derived from various origins such as leaf, bast, fruit, grass or cane; contribute to the strength of bio as well as synthetic polymer composites in various applications. These fibres are renewable, non-abrasive to process equipment, and can be incinerated at the end of their life cycle for energy recovery as they possess a good deal of calorific value. They are also very safe during handling, processing and use. Major natural fibres of vegetative origin used as reinforcement are shown in Table- 1. Both thermoset and thermoplastic matrices are used for development of natural fibre reinforced composite, the comparative study of these two type of matrices are shown in Table- 2 2 Table: 1 Major natural fibres of vegetative origin used as reinforcement Fibre Type Bagasse Cane Bamboo Grass Banana Stem Coconut husk Fruit Flax Bast Hemp Bast Jute Bast Kenaf Bast Sisal Leaf Wood Stem Advantages of natural fibre reinforced composites: Reduction in density of products. Acceptable specific strength, toughness and stiffness in comparison with glass fibre reinforced composites. Ease of shaping into complex shapes in a single manufacturing process. Lower energy consumption from fibre growing to finished composites The manufacturing processes are relatively safe when compared with glass based reinforced composites. Possibility of recycling the cuttings and wastage produced during manufacturing and moulding. The production of natural fibres can be started with a low capital investment and with a lower cost. Bast fibres exhibit good thermal and acoustic insulation properties. 3 Table: 2 Summary of advantages and disadvantages of thermoset and thermoplastics as matrix Property Thermoset Thermoplastics Formulations Complex Simple Melt viscosity Very low High Fibre impregnation Easy Difficult Prepeg stability Poor Excellent Processing cycle Long Short to long Processing temperature Low to moderate high High / pressure Environmental durability Good Unknown Solvent resistance Excellent Poor to good Database Very large Small The typical basic inherent characteristics of lignocellulosic fibre are shown in Tables- 3 & 4. Table: 3 Cell wall polymers responsible for the properties of lignocellulosics in the order of importance Biological Degradation Moisture Sorption Ultraviolet Degradation Hemicellulose Hemicellulose Lignin Accessible Cellulose Accessible Cellulose Hemicellulose Non-Crystalline Cellulose Non-Crystalline Cellulose Accessible Cellulose Lignin Non-Crystalline Cellulose Crystalline Cellulose Crystalline Cellulose Thermal Degradation Strength Hemicellulose Crystalline Cellulose Cellulose Matrix (Non-Crystalline Cellulose + Hemicellulose + Lignin) Lignin Lignin Ref: Chemical modification of agro-resources for property enhancement, Paper and Composites from Agro-based resources. CRC Press, Boca Raton, 1996 4 Table: 4 Degradation reactions that occur when lignocellulosic resources are exposed to nature. Biological Degradation Fire Degradation Fungi, Bacteria, Insects, Termites Lighting, Sun, Man Enzymatic Reactions Pyrolysis Reactions Chemical Reactions Water Degradation Weather Degradation Rain, Sea, Ice, Acid Rain Ultraviolet Radiation, Water, Heat, Wind Water Interactions Chemical Reactions Mechanical Degradation Dust, Wind, Hail, Snow, Sand Mechanical Ref: Chemical modification of agro-resources for property enhancement, Paper and Composites from Agro-based resources. CRC Press, Boca Raton, 1996 Disadvantages of natural fibre reinforced composites: Lack of consistency of fibre quality, high level of variability in fibre properties depending upon source and cultivars. Preparation of fibre is labour intensive and time consuming. Poor compatibility between fibres and matrix, which requires surface treatment of fibres. High moisture absorption, which brings about dimensional changes in composite materials. Low density of bast fibres can be disadvantageous during composites processing application because fibre tends to migrate to the surface rather then getting mixed with matrix. Fluctuation in price depending upon the global demand and production. Problem of storing raw material for extended time due to possibility of degradation, biological attack of fungi and mildew, loss in colour, and foul odour development. Lower resistance to ultra violet radiation, which causes the structural degradation of the composites. 5 Major R & D Work at IJIRA Extensive R & D work has been carried out at IJIRA on jute reinforced composite since early 80’s. The first work was carried out in collaboration with AERE, Harwell, U.K. using high performance matrices i.e. epoxy, polyester etc. to compare with mainly glass fibre reinforced composites. From late 80’s the objective was concentrated to develop wood substitute by jute composite targeting packaging and building materials. Low density polyethylene films were used with jute non-woven and fabric for fabrication of jute composite. These were tried for packaging of tea & horticultural produce. Some of the mechanical properties are given in Tables-5 & 6. Table: 5 Flexural Properties of jute composite from jute nonwoven and low density polyethylene as matrix Sl. Samples Flexural Strength Flexural Modulus Strain (MPa) (MPa) % 31.84 1433 8.013 No. 1. Jute non-woven* + LDPE film *Jute nonwoven- unidirectional & 400 gsm (nominal) *LDPE film- 50 gsm Ref: “Studies on jute composite from jute nonwoven”, 16th Technological conference, IJIRA, 11th – 12th Feb, 1993 Table: 6 Properties of jute composite from jute nonwoven and low density polyethylene as matrix for packaging end- uses. (IIP- Kolkata) Material Average test value Gram/m2 Puncture Water Bursting Tensile Mod. of resistance absorption str. str. elasticity oz-inch (surface) Kg/cm2 (MPa) (MPa) tear inch 24 hrs at 30 45.3 31.36 1756 C, gm/m2 Jute non- 1470 577.1 20.7 woven + LDPE film Ref: “Studies on jute composite from jute nonwoven”, 16th Technological conference, IJIRA, 11th – 12th Feb, 1993 6 Lignocellulosic fibres are favourably bonded with phenolic resin to have better water resistance rather than urea or melamine resin. Hence, water soluble phenol formaldehyde resin was selected for the development of rigid jute board for good serviceable mechanical properties. To achieve better wetability of jute with resin and to improve strength properties, fibre pre-treatment is necessary. Simple pretreatment is done with low-condensed resins like melamine resin, phenolic resin and CNSL modified phenol formaldehyde resin. Indicative physical properties of jute composites from untreated & pre treated jute nonwoven with PF resin are shown in Table-7. Jute as other lignocellulosic fibres consists of –OH group which causes it susceptible to moisture and directly impairs the properties of jute composite specially dimensional stability. Due to this polar group, jute also is not efficiently adhered to non polar matrices. To overcome this difficulties this fibre should be modified chemically or hygrothermally. To improve the interface adhesion between the non polar matrices and hydrophilic fibre, coupling agent or compatibiliser should be used. Some investigations were done by cyanoethylation and acetylation of jute fibre to reduce the –OH content. The both processes are effective for dimensional stability. Cyanoethylation also improves the bonding between jute and non polar matrix like unsaturated polyester resin. Indicative properties of jute composites made from modified fibres with urea formaldehyde resin & unsaturated polyester resin (USP) are given in Tables-8 & 9. 7 Table: 7 Physical properties of different jute composites Sl. Samples No. Tensile Flexural Flexural strength strength strength (Dry) (After 2 hrs. (MPa) (MPa) boiling in water) (MPa) 1. Untreated non- 42.10 68.24 22.17 49.99 73.97 27.50 47.70 72.32 26.13 62.21 90.03 58.27 woven* + PF resin 2. MF pretreated nonwoven + PF resin 3. PF pretreated nonwoven + PF resin 4. CNSL – PF pretreated nonwoven + PF resin Ref: “Studies on jute composite from jute nonwoven”, 16th Technological conference, IJIRA, 11th – 12th Feb, 1993 Table: 8 Effect of Cyanoethylation on Mechanical Properties of jute composites Sample Control Tensile Strength (MPa) Flexural Strength (MPa) Flexural Mod (GPa) 74.24 84.81 12.97 Water absorption % Thickness swelling % 2hr in boiling water 24hr in cold water 2hr in boiling water 24hr in cold water 48.09 49.76 62.31 31.94 MJC-4 108.60 136.90 18.05 12.46 5.45 12.97 10.36 Ref: “Improvement of functional properties of jute based composite by acrylonitrile pretreatment”, J. of Applied Polymer Science, vol. 78, 495-506 (2000) 8 Table: 9 Effect of Acetylation on Mechanical Properties of jute composites Sl. Samples No. Tensile Flexural Thickness % Retention % Retention of strength strength swelling % of tensile flexural strength (MPa) (MPa) strength after after 5 cyclic 5 cyclic test test (immersion (immersion & & oven dry) 1 hr 7 days oven dry) 1. CNa 62.92 39.13 29.00 40.80 30.35 24.12 2. ANa 66.66 42.33 17.50 23.00 50.25 50.34 3. CNH 56.25 37.12 23.5 37.55 29.35 26.25 4. ANH 57.22 39.00 14.00 20.00 48.77 49.47 5. CMF 49.58 40.21 17.00 20.70 55.70 55.12 6. AMF 60.04 44.45 13.36 18.9 61.12 59.33 Jute sliver + 25% UF resin including additives CNa- control jute sliver with NaCl and UF resin; ANa- acetylated jute sliver with NaCl and UF resin; CNH- control jute sliver with NH4Cl and UF resin;ANH- control jute sliver with NH4Cl and UF resin; CMF- control jute sliver with melamine and UF resin; AMF- control jute sliver with melamine and UF resin; Ref: “Effect of acetylation on dimensional stability, mechanical and dynamic properties of jute board”, J. of Applied Polymer Science, vol.72, 935-944 (1999) Hygrothermal pretreatment on jute fibre was done by spraying extra water on fibre and was formed in square mat. The mat was placed in a closed mould and pressed at 200 C for a few minutes to modify the fibre. These modified fibres were moulded with PF resin as normal compression moulding process. Here the dimensional properties have been improved but the other mechanical properties have been reduced drastically due to thermal degradation of fibre and shown in Table- 10. 9 Table: 10 Effect of Steam Pretreatment on properties of jute composites Samples Flex. Str. kg/cm2 Flex. Mod. Kg/cm2 Water absorption % 24 h. 2 h boiling Control 127.32 18578.84 166.57 137.13 SB4 39.28 12682.42 95.6 90.94 SRB4 85.87 13963.74 64.3 64.5 SB8 24.46 7412.00 88.93 87.26 SRB8 77.68 8825.40 56.75 60.18 Control- board from jute fibre + 7% PF; Thickness swelling % 24 h. 2 h boiling 77.65 97.27 18.69 24.45 16.07 24.24 11.98 21.67 11.52 21.09 SB4- board from 4 min. steam stabilized fibre. SB8- board from 8 min. steam stabilized fibre. SRB4- board from 4 min. steam stabilized fibre + 7% PF SRB8- board from 8 min. steam stabilized fibre + 7% PF Ref: “Effect of steam pretreatment of jute fibre on dimensional stability of jute composite”, J. of Applied Polymer Science, vol.76, 1652-1661 (2000) Process steps for fabrication of jute composite from thermoset resin: Impregnation & drying- jute substrate (nonwoven / woven fabric) is dipped in resin solution and squeezed to retain the required amount of resin and then passed through dryer to reduce the moisture. Cutting of substrate- The treated substrate is cut to size as per dimension required. Compression moulding- Books inside the platen are pressed to desired specific pressure and temperature for pre defined time to get moulded product. After completion of compression cycle, the platens are cooled to optimum temperature & then the pressure is released to take out the products. Post curing- Compression moulded products are post cured in oven to get fully cured and free from any precondensate polymer. Cutting & sanding- The moulded product is trimmed and sanded. For continuous moulded profile from jute reinforced composite, thermoplastic matrix (PP) was used for melt blend with jute. In this process short jute fibre was melt blended with polypropylene granules in presence of compatibilizer maleated polypropylene. The properties are optimized on 60% jute fibre with 38% polypropylene and 2% maleated polypropylene (Table- 11). 10 Table: 11 Effect of Compatibiliser on Mechanical Properties of Jute-PP composites Sample J600 Tensile Strength(MPa) 33.5 Tensile Modulus(GPa) Flexural Flexural Strength(MPa) Mod(GPa) 10.35 J602 68 10.50 J600- Jute fibre 60%, Polypropylene 40% Water Absorption % 2hr in boiling water 24hr in cold water 57.50 10.02 3.06 1.86 109 10 2.22 0.91 J602- Jute fibre 60%, Polypropylene 38%, Maleated polypropylene 2% Ref: “Short jute fibre reinforced polypropylene composites: Effect of compatibiliser”, J. of Applied Polymer Science, vol.69, 329-338 (1998) Process steps for melt blend of jute PP: Chopping- Jute fibre was stapled unto 100 mm Granulating- Stapled jute fibres were further reduced in size unto 10 mm (max) by passing through rotary granulating m/c Mixing- Short jute fibres with matrix were mixed in Kinetic mixer m/c at 5500 rpm & 199 C to form dough Pressing- Hot dough of mixture was flattened by pressing with hydraulic press to release excess heat Reduction of size- Flattened dough sheet was cut into pieces by running through band saw Granulating- Small pieces were further reduced in size by running through granulator. Injection molding- Granules of jute-pp were injection moulded to test pieces. Age old practice of fabrication of reinforced product is hand lay-up process. But resin consumption is very high and productivity is very low due to long processing time. New moulding technique, i.e. Resin Transfer Moulding, is used to replace hand layup process for better productivity and quality. Resin transfer moulding literally means the transfer of the matrix under pressure to the closed mould containing the reinforcing substrate. This is the inverse process of vacuum moulding. Mainly unsaturated polyester resin was used as matrix. Work was done to evaluate the influence of jute as an additional substrate with glass and some of the properties are shown in Table- 12 11 Table: 12 Flexural Properties of jute and jute-glass fibre composites fabricated by resin transfer moulding Sl. no Weight of fibre Flex. Str. Flex. Mod. % (MPa) (GPa) Jute Glass Total 1 33 -33 95.65 6.65 2 28 -28 82.55 5.85 3 18 15 33 121.51 6.88 4 -33 -153.77 7.12 Ref: “Jute composites by Resin Transfer Moulding- An improved alternatives for hand lay up technique”, 20th Technological Conference, April 18, 1998 Pultrusion is a modern technique used for producing continuous fibre reinforced profile in which the orientation of the fibre is kept constant during cure. This process is suitable for thermosetting resins like polyester, epoxy & phenolic resin systems. An infinite number of profiles can be produced using appropriate dies and includes rods, tubes, flat & angle sections. Pultrusion technique has been utilized for making door frame using jute as reinforcement and phenol formaldehyde resin as matrix. This has been evaluated by Central Building Research Institute, Roorkee & shown in the Table- 13. Table: 13 Physico-mechanical properties of pultruded jute profile Property Value A. Physical properties Bulk density (Kg/m3) 873 Moisture content (%) 4.41 Water absorption (%) I. 2 hrs. 3.61 II. 24 hrs. 12.31 Surface water absorption (24 hrs., %) 1.52 Change in swelling (%) I. Thickness 0.37 II. Length 0.013 III. width 0.041 Due to surface absorption (%) Negligible B. Mechanical properties Flexural yield strength (MPa) 62.60 Modulus of elasticity (GPa) 5.31 Tensile strength (MPa) 33.0 Elongation (%) 0.86 Tensile modulus (GPa) 7.98 Internal bond strength (MPa) 0.66 Screw withdrawal strength (N), Face 1800 Ref: “Suitability assessment of JRP Pultruded profile as door frame materials in building”, Report No. F(C) 0176, Feb. 1998, Organic Building Materials Division, CBRI, Roorkee. 12 Application areas of jute reinforced polymer composites with technical advantages Application areas Advantages Automobile industries door panels seat backs headliners, dash boards trunk liners Building Component Door Window Wall partition Ceiling Floor Transport Sector (railway coach & vehicle) Flooring Ceiling Seat & Backrest Furniture Table Chair Kitchen cabinet etc. Lighter in weight Lesser raw material Cost economic Serviceable mechanical properties Use of renewable resource Better physical properties Fire, termite & better moisture resistance properties Available at semi finished / finished state i.e. reduced labour & finishing cost Better physical properties Fire, termite & better moisture resistance properties Available at semi finished / finished state i.e. reduced labour & finishing cost Better physical properties Fire, termite & better moisture resistance properties Available at semi finished / finished state i.e. reduced labour & finishing cost Future R & D plan Broadly defined bio-composite are composite materials made from natural fibre and petroleum derived non biodegradable polymers like polyester, phenolic, PP etc. These polymer matrices are becoming costlier because of the fluctuating price of petrochemicals. These resins could be made cheaper by modification with cheaper bio-resources. Bio-composite derived from plant fibre & crop / bio-derived plastic are likely more eco-friendly and such bio-composites are termed as green composite. Future attempt would therefore be to develop cheaper biodegradable matrix utilizing modification of bio-resources. 13