Crystallization Behaviors and Morphology of Polypropylene Containing Nucleating and Degradation Agents

Abstract

The effect of 1,3;2,4-di-benzylidene sorbitol (TM-3) and/or dicumyl peroxide (DP) on molecular structure development, crystallization behaviors, and crystal structure of polypropylene (PP) was studied by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), polarized optical microscope (POM), and wide angle X-ray diffraction (WAXD). The GPC results show that the addition of DP causes the molecular weight of PP to decrease, and its distribution becomes narrower. The DSC results suggest that the PP chains become more difficult to unentangle when treated by the nucleating agents, which should be responsible for the difference in the nucleation effects. The DP has little nucleation effect on the crystallization of bulk PP; however, it can make it much easier to unentangle and accelerate the nucleation and crystallization of the bulk PP in PP/TM-3/DP. As well, the spherulites of PP become much smaller and disperse more uniformly. The β -form crystal phase disappears in PP/DP and PP/TM-3/DP samples due to decreasing molecular weight and narrowing molecular weight distribution.