Crystallization and foaming of coagent-modified polypropylene: Nucleation effects of cross-linked nanoparticles

The radical-mediated addition of trimethylolpropane trimethacrylate (TMPTMA) to linear, isotactic polypropylene (PP) yields graft-modified derivatives that contain coagent-rich, cross-linked particles with sub-micron dimensions. The presence of this dispersed phase in coagent-modified polypropylene (CM-PP) is shown to increase the crystallization temperature and crystallization rate, owing to an enhanced heterogeneous nucleation mechanism. Analogous enhancements in nucleation are also demonstrated for a batch foaming process, wherein N2 is used as a physical blowing agent.