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In this study, poly (lactic acid) (PLA) blended with various rubber components, i.e., poly (ethylene‐glycidyl methacrylate) (EGMA), maleic anhydride grafted poly(styrene‐ethylene/butylene‐styrene) triblock elastomer (m‐SEBS), and poly(ethylene‐co‐octene) (EOR), was investigated. It was observed that EGMA is highly compatible due to its reaction with PLA. m‐SEBS is less compatible with PLA and EOR is incompatible with PLA. Electron microscopy (SEM and TEM) revealed that a fine co‐continuous microlayer structure is formed in the injection‐molded PLA/EGMA blends. This leads to polymer blends with high toughness and very low linear thermal expansion both in the flow direction and in the transverse direction. The microlayer thickness of rubber in PLA blends was found to play key roles in reducing the linear thermal expansion and achieving high toughness of the blends. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

The electrical, crystallization and thermal expansion behaviors of polyamide 610 (PA610)/multi-walled carbon nanotube (CNT) nanocomposites prepared by melt mixing were investigated. Electron microscopy (Scanning Electron Microscopy and Transmission Electron Microscopy) revealed that a good dispersion of CNT and CNT networkwas obtained in the PA610 matrix. Addition of CNT to PA610 matrix led to polymer nanocomposites exhibiting higher electrical conductivity and lower thermal expansion. The network of CNT in the PA610 matrix, which can be tuned by the loading of CNT and the melt isothermal treatment, was found to play an important role in reducing thermal expansion and achieving higher conductivity. Furthermore, it was shown that significant reduction in thermal expansion in PA610/CNT nanocomposites was due to both thermally insensitive CNT and formation of CNT network.

An ethylene–propylene–diene terpolymer/isotactic polypropylene blend with a structure of co‐continuous microlayers was fabricated by injection molding and was then investigated. The blend exhibited an extremely low coefficient of linear thermal expansion (CLTE) in the directions of the length and the width. As the thickness of the oriented portion increased, the CLTE was further reduced. The morphology of the co‐continuous microlayers and the thermal expansion behavior varied with the sampling positions on the injection‐molded sheets. To study the relationship between the morphology and the melt flow, the melt flow behavior during injection molding was simulated using Moldflow. Orientation of the microlayers was determined using shear flow. When the shear rate increased, the orientation state increased and the CLTE decreased. © 2015 Society of Chemical Industry

Fine regulation of the microstructure of rubber/polypropylene (PP) alloys could remarkably reduce the coefficient of linear thermal expansion (CLTE) while retaining the mechanical properties similar to those of thermoplastic elastomers. Rubber/PP elastomers with different morphologies were successfully prepared by controlling the appropriate rubber type, viscosity ratio, and processing method. The CLTE of the polymer alloy parallel to the microlayer directions was considerably reduced when the rubber domains were deformed into microlayers and co‐continuous with plastic domains. The thickness of the PP layers played a crucial role on CLTE reduction. The CLTE considerably decreased with reduced thickness of the PP layer. The sample with a co‐continuous microlayer structure exhibited good flexibility, high elongation, low hardness, and permanent deformation. Thus, low‐thermal‐expansion elastomer materials may have wide applications. Stress relaxation and strain recovery of the ethylene–propylene–diene terpolymer/PP (70/30 wt %) blend were investigated to further clarify the influence of co‐continuous microlayer structure on mechanical properties. Anisotropic mechanical properties were consistent with the morphology. Results of the stress relaxation behavior test would provide further support to the mechanism of the low thermal expansion of blends with co‐continuous microlayer structure. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43902.

The effect of organoclay on phase morphology development of PA6/SEBS alloys had been investigated. PA6/SEBS blends of various compositions, with and without the presence of exfoliated organoclay in the PA6 phase, were prepared and the morphology and thermal expansion of these blends were examined. The results suggested that at compositions where PA6 remains as the matrix domain, the presence of the organoclay had little or no effect upon the blends morphology, PA6/SEBS alloy with SEBS as the matrix could evolve from sea‐island to cocontinuous structure after 5 phr organoclay were added. Significant reduction in the coefficient of linear thermal expansion (CLTE) along theflow direction and furthermore improving the heat distortion temperature of the injection‐molded PA6/SEBS/organoclay ternary nanocomposites was observed due to the formation of a total stable and fine cocontinuous nanolayer structure. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

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