Abstract: Differential scanning calorimeter was used to characterize the non-isothermal crystallization of polypropylene/ultra high molecular weight polyethylene (PP/UHMWPE) blends, with the data analyzed with Ozawa、Mo Zhishen, and Kissinger methods. Extrusion foaming experiments on PP/UHMWPE blends were carried out on a self-made super critical liquid foam equipment. It showed that in presence of UHMWPE, the crystallization activation energy of PP decreased, the crystallization rate decreased, and PP began to crystallize at a higher temperature with the addition of UHMWPE. The existence of macromolecullar chain of UHMWPE and entanglement with PP obstructed molecullar chain of PP into the lattice,so the crystallization temperature increased and the crystallization temperature range broadened, which resulted in obvious improvement of foam performance of PP. When the content of PE-UHMW was 5 phr, the obtained apparent density of the extrudate was 0.038g/cm-3.

Key words: polypropylene(PP), ultra high molecular weight polyethylene(UHMWPE), crystallization kinetics, foamability