On Polyethylene Chain Generation Through Chemical Crosslinking of Isotactic Polypropylene

Crosslinked isotactic polypropylene (iPP) was prepared by reactive blending using dicumyl perox- ide and active sulfur. The modified material was characterized by means of several techniques: dynamic mechanical thermal analysis, differential scanning calorim- etry, Fourier transform infrared spectroscopy, and nuclear magnetic resonance ( 13 C solid state NMR). Analysis of results using the above techniques confirms that, during the crosslinking process, new ethylenic chains are gener- ated at expenses of the initially present iPP. Furthermore, a balance between the amount of missing iPP and the pro- portion of newly created polyethylene (PE) is observed. The newly formed PE is semicrystalline, having a degree of crystallinity of about 30%. The amorphous component of the generated PE is thought to contribute to the high impact strength of the crosslinked samples when com- pared to the unmodified iPP. In light of the results obtained by the different techniques, an attempt to describe the emerging structure of the new crosslinked iPP