Realizing simultaneous high‐temperature strength and low‐temperature elongation in polyolefin elastomer toughened polypropylene via controlling the dispersed phase size

Abstract The properties of modified polypropylene (PP) materials are closely related to their phase structure. In this work, polyolefin elastomer (POE)‐toughened PP materials with different phase structures were designed by using various types of POEs (ethylene‐butene 710, 110, ethylene‐propylene 6202, ethylene‐octene 8200). Then, the effects of phase separation in PP/POE blends on both thermal and tensile properties as well as ultraviolet (UV) resistance were investigated. The results revealed that the POE type hardly affected the melt flow rate, melting or crystallization behavior of the modified PP samples. Moreover, scanning electron microscopy results showed that POE6202 had a smaller dispersed phase size in PP (0.1–0.5 μm), which improved the low‐temperature elongation at break. PP/POE110 blends with a larger microdomain (1–5 μm) had better high‐temperature tensile strength. Further, when toughened with POE110 and POE6202 simultaneously, modified PP had excellent low‐temperature elongation (272%@ −40°C) without sacrificing as much of its high‐temperature tensile strength (10.4 MPa@70°C). Finally, Electron Paramagnetic Resonance tests showed that the addition of amorphous POE decreased the intensity of free radicals generated in PP during irradiation and promoted their attenuation during decay. This indicated that the introduction of POE improved the UV resistance of PP.