Rheological/crystallization behavior of PP/graphite nanosheet composites and performance of microcellular foaming plastics

Abstract

The large, uneven and distorted cells in foaming products seriously weakens its mechanical properties. Herein, a promising way to prepare lightweight and strong PP/graphite nanosheet(GN) nanocomposite foaming products is reported. To improve foaming performance, the effects of GN on the crystallization behavior and rheological behavior of PP are firstly systematically studied. It is found that the addition of GN not only directly improves the melt strength and viscoelasticity, but also has the dual effects of refining grain size and accelerating crystallization process. The excellent cellular structure with the average cell diameters of several microns is fabricated using m old-opening foaming injection molding (MOFIM) process, which contributes to enhanced mechanical properties. The tensile strength and modulus of PP/GN nanocomposite foams with opening distance of 1 mm is almost 50% and 70% higher than that of the neat PP solids, respectively. The nanocomposite foam also shows superior impact strength, increased to above 75% than that of the neat PP solids.