Experimental detection of a transcrystalline interphase in glass-fibre/polypropylene composites

Crystallization and melting behaviour of polypropylene in glass-fibre-reinf orced composites have been investigated by means of differential scanning c alorimetry. Composites with differently size-coated glass fibres show diffe rent behaviour both in dynamic and isothermal crystallization. A high cryst allization rate and a short induction time were observed for composites wit h unsized fibres at isothermal crystallization. Glass fibres sized with ami nosilane and polypropylene film-former revealed a quantitatively separable two-step crystallization process. With the assignment to the transcrystalli zation and spherulitic crystallization the thickness of the transcrystallin e PP interphase in this composite could be estimated to about 1 mu m. The i nfluence of transcrystallinity on the mechanical properties was discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.