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In this study, cyclic olefin copolymer/poly(ethylene-co-vinyl acetate) 90/10, 80/20, and 70/30 blends were prepared by melt processing in a twin screw extruder equipped with a cast film haul-off unit to make films. Microstructural, rheological, mechanical, and viscoelastic properties of film samples were investigated by various tests performed in scanning electron microscope, rotational rheometer, dynamic mechanical analyzer, and tensile test machine. We observed that the films exhibited characteristic immiscible ''matrix-droplet'' or ''cocontinuous'' blend morphology, depending on the sample composition. Based on the melt rheology and dynamic mechanical analyzer tests, we found that poly(ethylene-co-vinyl acetate) addition changed the viscoelastic properties of cyclic olefin copolymer such as increasing short-term creep strain and relaxation time but reducing relaxation rate in solid state. One can conclude that such effects became more pronounced by adding a compatibilizer (PE-g-MA) at 50% of poly(ethylene-co-vinyl acetate) present in the composition. We also found that poly(ethylene-co-vinyl acetate) addition into cyclic olefin copolymer reduced the Young's modulus and yield stress and increased the strain at break for the blends.

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In this study, physical properties of high‐density polyethylene (HDPE) films, blended and reinforced with small amounts of liquid crystal polymer (LCP) and organoclay (org‐clay), were investigated by employing different characterization tools such as X‐ray diffractometer, scanning electron microscope, differential scanning calorimetry, rotational rheometer, dynamic mechanical analysis, and gas permeability measurements. Viscoelastic properties of samples were quantified by applying several test procedures in melt and solid‐state dynamic measurements. It was found that rigid LCP droplets were dispersed well into HDPE matrix and improved the melt elasticity and creep resistance of HDPE. Compatibilizer and org‐clay loading into HDPE/LCP blends yielded formation of smaller LCP droplets and reduced mean relaxation time and shear modulus values, compared to unloaded counterparts. It was observed that org‐clay stacks were dispersed into HDPE phase due to using of maleic anhydride grafted polyethylene as compatibilizer and HDPE/LCP/org‐clay ternary nanocomposites exhibited intercalated microstructure. Solid‐state uniaxial tensile creep behaviors of films were modeled with the Findley power‐law and four‐element Burger models. HDPE/LCP/org‐clay (90/10/5) ternary nanocomposite film exhibited better gas barrier performance than HDPE by decreasing its permeability by 50%. POLYM. ENG. SCI., 59:1344–1353 2019. © 2019 Society of Plastics Engineers

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