Strong synergistic improvement of mechanical properties in HDPE/COC blends with fibrillar morphology

Abstract

High‐density polyethylene/cycloolefin copolymer (HDPE/COC) blends with fibrous morphology were prepared. Mechanical properties in the whole concentration range were measured in both macroscale (tensile measurements) and microscale (microindentation hardness testing). Strong improvement of mechanical performance was observed namely for the blends with soft HDPE matrix reinforced with the stiff oriented COC fibers. The combined results from scanning electron microscopy, mechanical properties measurements and theoretical calculations based on predictive models showed that the interfacial adhesion was unusually high, which could be attributed to the excellent compatibility or even partial miscibility of the blend components. The HDPE/COC blends with 10–40% of COC showed the synergistic improvement of the tensile energy to break (ETB) that exceeded the ETB of both individual components. Also the stiffness of the blends, represented by the elastic modulus, the yield strength and the microhardness were very high, above the theoretical values predicted by the equivalent box model. POLYM. ENG. SCI., 58:1955–1964, 2018. © 2017 Society of Plastics Engineers