Effect of multiple extrusion on phase structure and properties of impact copolymerized polypropylene

Abstract

As a typical multi-component polymer, impact polypropylene copolymer (IPC) experiences the phase structure evolution during repeated processing, and the coarsening of phase domain often occurs. In this work, two IPCs with different molecular weight of rubber phase were compared systemically. The evolution of IPC phase morphology and crystallization behavior after multiple extrusion were studied through scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The materials mechanical properties were tested. Then the influence of rubber phase molecular weight on the phase morphology evolution and the properties after repeated extrusion were discussed in detail. It was found that for the IPC with low molecular weight of rubber phase, the size of rubber phase became smaller and dispersed more evenly with the increase of extrusion times; for the IPC with high molecular weight of rubber phase, the rubber phase size turned to unstable after multiple shearing. The rubber phase size had a complex effect on IPC mechanical properties.