Impact-resistant polypropylene/thermoplastic polyurethane blends: compatible effects of maleic anhydride on thermal degradation properties and crystallization behaviors

In this study, impact-resistant polypropylene (MPP), thermoplastic polyurethane (TPU) and polypropylene-grafted maleic anhydride (MA) are made into MPP/TPU/MA blends using melt-compounding and injection methods. The blending morphology, crystallization behavior, and melting and thermal behaviors of the blends are evaluated in terms of the content of TPU and MA, examining the influences of the parameters. The scanning electron microscope (SEM) observation shows that 1 wt% of MA can effectively enhance the interfacial adhesion and compatibility between MPP and TPU. The differential scanning calorimetry (DSC) results show that the crystallization temperature and melting temperature of the blends are not dependent on the content of TPU or MA. However, using TPU and MA adversely affect the crystalline and melting enthalpy of the blends. The thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) curve both show that the higher the MPP, the greater the thermal stability of TPU. Likewise, using MA as compatibilizer also has a positive influence on the thermal stability of the blends. The X-ray diffraction (XRD) analyses confirm that the addition of TPU decreases the diffraction intensity of MPP, but does not harm the crystalline structure of MPP. Moreover, the addition of MA improves the compatibility between MPP and TPU. MA marginally decreases the peak value and does not influence the crystallinity degree of MPP. It is expected that the results of SEM, DSC, TGA, DTG, and XRD can serve as a valuable reference for the design of composites with improved thermal and crystallization behaviors. Keywords: Impact-resistant polypropylene, Thermoplastic polyurethane, Maleic anhydride, Thermogravimetric analysis, Derivative thermogravimetry, Blends, Crystallization