Enhancing the mechanical properties and foaming performance of polypropylene through melt grafting reaction by using trimethylolpropane triacrylate

Ordinary polypropylene homopolymer (PP) has low melt strength and mechanical properties, which greatly restricts its application in foam molding. In this work, high melt strength polypropylene (HMSPP) is successfully fabricated by melting grafting technique using dicumyl peroxide as an initiator and trimethylolpropane triacrylate (TMPTA) as a grafting monomer. The effects of different reaction temperatures and formulas on modified PP are investigated. The results show that the introduction of TMPTA will reduce the melt flow rate, and improve the grafting ratio, torque, melt strength (MS), mechanical properties, thermal stability, and crystallization rate of polypropylene. It is found that HMSPP prepared at 170 °C 1.2 Phr TMPTA has the best comprehensive properties, with MS increased by 3.8 times, elongation at break increased by 120%, flexural modulus increased by 25%, impact strength increased by 33.3%, and thermal decomposition temperature increased by 52.6 °C. In addition, PP/HMSPP is extruded and foamed, and the results show that the foaming performance of HMSPP is better than that of PP. In general, the introduction of TMPTA improves the mechanical properties, melt strength, foaming property, and thermal stability of PP. Graphical abstract