Morphology and properties of nanocomposites formed from ethylene-vinyl acetate copolymers and
organoclays
Lili Cuia, Xiaoyan Maa, b and D.R. Paula, Corresponding Author Contact Information, E-mail The Corresponding Author
aDepartment of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712, USA
bDepartment of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China
Abstract
A series of ethylene-vinyl acetate copolymers, EVA, containing 0–40% VA and three organoclays, M2(HT)2,
M3(HT)1 and (HE)2M1T1, were melt processed to explore the relationship between the polarity of the polymer
matrix and the organoclay structure on the extent of exfoliation and properties of the resulting
nanocomposites. The degree of exfoliation of the nanocomposites was evaluated by TEM, WAXS, and
mechanical testing. Quantitative particle analyses of TEM images were made to give various averages of the
clay dimensions and aspect ratio. The results from different techniques were generally consistent with each
other. These EVA copolymer nanocomposites show dramatically improved exfoliation of the organoclay as the
VA content is increased. Nanocomposites based on the organoclay with two alkyl tails always gave better
exfoliation than those based on the organoclays with a single tail at all VA levels; however, the relative
advantage of the two tails versus one tail seems to diminish with increased VA level. The predictions of tensile
modulus using a simple composite model based on Halpin–Tsai equations show rather good agreement with
the experimental data.
Keywords: Ethylene-vinyl acetate copolymers; Nanocomposites; Organoclays
Polymer
Volume 48, Issue 21, 5 October 2007, Pages 6325-6339
Thermo-mechanical properties of the blend syndiotactic/atactic polystyrene after crystallization of the
syndiotactic polystyrene
Martin Bonnet1, Maren Buhk1 and Jürgen Petermann1
(1)
Department of Chemical Engineering, Institute of Material Science, University of Dortmund, Emil-Figge-Strasse 66, D-44221 Dortmund,
Germany, DE
Abstract
The thermo-mechanical properties of the blend syndiotactic polystyrene (sPS)/ atactic polystyrene (aPS) are
characterized by studying the concentration depending softening behavior with thermo-mechanical analysis
(TMA) and the temperature depending Young's modulus for different concentrations with dynamic mechanical
analysis (DMA).
Journal Polymer Bulletin
Issue
Volume 42, Number 3 / March, 1999
Evaluation of amine functionalized polypropylenes as compatibilizers for polypropylene nanocomposites
Lili Cuia and D.R. PaulCorresponding Author Contact Information, a, E-mail The Corresponding Author
aDepartment of Chemical Engineering and Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712-1062, USA
Abstract
The compatibilization effects provided by amine functionalized polypropylenes versus those of a maleated
polypropylene, PP-g-MA, for forming polypropylene-based nanocomposites were compared. Amine
functionalized polypropylenes were prepared by reaction of maleated polypropylene, PP-g-MA, with 1,12diaminododecane in the melt to form PP-g-NH2 which was subsequently protonated to form PP-g-NH3+.
Nanocomposites were prepared by melt processing using a DSM microcompounder (residence time of 10 min)
by blending polypropylene and these functionalized materials with sodium montmorillonite, Na-MMT, and
with an organoclay. X-ray and transmission electron microscopy plus tensile modulus tests were used to
characterize those nanocomposites. Composites based on Na-MMT as the filler showed almost no
improvement of tensile modulus compared to the polymer matrix using any of these functionalized
polypropylenes, which indicated that almost no exfoliation was achieved. All the compatibilized
nanocomposites using an organoclay, based on quaternary ammonium surfactant modified MMT, as the filler
had better clay exfoliation compared to the uncompatibilized PP nanocomposites. Binary and ternary
nanocomposites using amine functionalized polypropylenes had good clay exfoliation, but no advantage over
those using PP-g-MA. The PP-g-MA/organoclay and PP/PP-g-MA/organoclay nanocomposites showed the most
substantial improvements in terms of both mechanical properties and clay exfoliation.
Keywords: Polypropylene; Nanocomposites; Compatibilizer
Polymer
Volume 48, Issue 6, 8 March 2007, Pages 1632-1640
Grafting of 3-(trimethoxysilyl)propyl methacrylate onto polypropylene and use as a coupling agent in viscose
fiber/polypropylene composites
T. Paunikallioa, M. Suvantoa and T.T. PakkanenCorresponding Author Contact Information, a, E-mail The Corresponding Author
aUniversity of Joensuu, Department of Chemistry, P.O. BOX 111, FIN-80101 Joensuu, Finland
Abstract
In this work, 3-(trimethoxysilyl)propyl methacrylate (MPTMS) was grafted onto polypropylene (PP) with use of
dicumyl peroxide (DCP) as initiator in a twin screw extruder. Two batches of the grafted PP (PPgSIL) were
prepared corresponding to two different grafting levels (4 and 8 wt.%). The presence of MPTMS in the PPgSIL
samples was confirmed by FTIR, 1H NMR, and elemental analysis. DSC and GPC results showed that the melting
point(s) and molar mass of the PP were reduced due to the grafting. The two PPgSIL batches were used as
coupling agents in viscose fiber/PP composites, each at three different levels (5, 2, and 1 wt.% of the weight of
the composite). PPgSIL had a significant effect on the mechanical properties of the composites. The composites
where PPgSIL was applied, the tensile strength increased by 59% relative to the composites without PPgSIL
(64.6 MPa vs. 40.7 MPa). For comparison, the viscose fibers were treated with MPTMS in 1 wt.% MPTMS/water
solution; however, the improvement in mechanical properties of the viscose fiber/PP composites was
considerably less than that achieved with the PPgSIL coupling agent (46.6 MPa vs. 64.6 MPa).
Keywords: Polypropylene; Grafting; Coupling agent; Homopolymerization; 1H NMR
Reactive and Functional Polymers
Volume 68, Issue 3, March 2008, Pages 797-808
Reduced Cost Fabrication of Large Composite Aerospace Structures Through Nanoparticle Modification of
Thermoplastics (Preprint)
Authors: Gregory R. Yandek; Darrell Marchant; Joseph M. Mabry; Mark B. Gruber; Mark Lamontia; Sandra Cope; ENGINEERING RESEARCH AND
CONSULTING INC (ERC INC) EDWARDS AFB CA
Abstract
To achieve superior mechanical properties and environmental durability in semi-crystalline engineering
thermoplastic composites an intermediate degree of molecular ordering is required. While many
thermoplastics achieve their potential crystallinities with autoclave processing, only a fraction of that which is
desired is developed with lower cost manufacturing processes, viz. automated fiber placement and tape laying
featuring polymer chilling from the melt in seconds. Implementation of such processes for the manufacture of
large composite aerospace structures is therefore rooted in material selection and the minimization of cycle
times. Polyetheretherketone (PEEK) has demonstrated utility in composite structures due to its processing
behavior. The cost-driven replacement of PEEK with other materials depends whether desired laminate
crystallinities may be attained avoiding costly annealing steps. Polyetherketoneketone (PEKK) represents an
alternative but suffers from reduced crystallization rates. The use of nucleating agents presents a route
towards enhancing the ordering phenomena in polymers. A study has been undertaken to evaluate the
effectiveness of utilizing silicon-based nanoparticles in improving the crystallization kinetics of PEKK. Relevant
findings including the impact of the addition of such nanoparticles on other properties will be discussed.
Keywords relating to this report: AEROSPACE SYSTEMS , THERMOPLASTIC COMPOSITES , COMPOSITE
MATERIALS , FABRICATION , LAMINATES , MECHANICAL PROPERTIES , NANOTECHNOLOGY , NUCLEATE BOILING
, STRUCTURES.