DSC analysis of crystallization and melting behavior of polypropylene in model composites with class and poly(ethylene terephthalate) fibers

Isothermal and nonisothermal crystallization of maleic anhydride grafted po lypropylene (PP), which is used for the production of split warp knit compo site preforms,(1) are analyzed in model composites to determine the influen ce of reinforcement glass fibers (GF) and poly(ethylene terephthalate) (PET ) binding yarns on the crystallization kinetics. Basic energetic parameters of crystallization are determined, and the melting behavior of PP in model composites is analyzed. The crystallization of PP carried out in nonisothe rmal and isothermal regimes is facilitated in the presence of GF, and the a dditional effects of PET fibers are also shown. Better conditions for nucle ation, resulting in lower energy for formation of a stable nucleus and lowe r critical dimensions, are proposed as a reason for this. The crystal struc ture of PP in model composites exhibits lower lamellae thickness and is les s disposed to recrystallization. (C) 1999 John Wiley & Sons, Inc.