The effect of nucleation specificity on thermal behaviour of photodegraded polypropylene

Abstract

This work focuses on thermal behaviour of UV-irradiated polypropylenes (PP) containing α- or βnucleating agents or their combination. After irradiation the samples were melted, then non-isothermally crystallized and subsequently melted again. It was found that β-nucleated PP possessed the highest UV-stability. The photodegradation was also suppressed in materials containing α-nucleating agent. The effect of UV-irradiation led to a splitting of crystallization exotherms into two peaks. The strong efficiency of α-nucleating agent used was reflected by predominant formation of αphase in non-irradiated material containing a combination of both α- and β-nucleating agents. However, after only 24 hrs of UV-irradiation this effect was reduced and a preferable formation into β-phase in re-melted material was detected.