Simultaneously Improving the Toughness, Flexural Modulus and Thermal Performance of Isotactic Polypropylene by α-β Crystalline Transition and Inorganic Whisker Reinforcement

Magnesium salt (M-HOS) whisker and beta-nucleating agent were introduced into polypropylene and their effects on the crystalline structures, morphologies, mechanical properties, and thermal resistance of polypropylene (PP) were investigated. The results of wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and polar optical microscopy (POM) examinations suggested that the presence of the whisker did not cause any negative effect on the occurrence of beta-modification, and beta-phase became absolutely dominant form in beta-nucleated samples. The mechanical and thermal properties tests demonstrated that there is an excellent synergy between the beta-nucleating agent and the whisker. For PP composite containing 0.1 wt% of the beta-nucleating agent and 10 wt% of the whiskers, the Izod notched impact strength, elongation at break, flexural modulus, and heat deflection temperature were increased by 108, 194, 31, and 40%, respectively, compared with those of neat PR By combining the toughening effect of alpha-beta transition with the reinforcing effect of the whisker, simultaneous improvement in toughness, flexural modulus, and thermal performance of PP was successfully achieved. POLYM. ENG. SCI., 50:222-231, 2010. (C) 2009 Society of Plastics Engineers