MODEL FOR PHASE-CHANGE KINETICS IN POLYMER COMPOSITES WITH SIGNIFICANT FIBER SURFACE NUCLEATION

A model for the isothermal crystallization of fiber-reinforced polymer s with significant nucleation on the fibers is presented. The model is based on exact and approximate expressions for the volume of intersec tion between a cylinder and a sphere located on the outside radius of the cylinder which allows to account for the effects of the fibers on the overall crystallization process. The crystallization process is di vided into time frames according to the validity of the solutions for the volume of intersection. The evolution of the crystallinity is comp uted for both thermal and athermal nucleation processes. The accelerat ing effect of fiber-nucleated spherulites on the overall crystallizati on process is demonstrated with simple examples in which parameters su ch as the fiber volume fraction, the fiber radius, the nucleation dens ity and an induction time are changed. Limitations of the current mode l are also discussed. (C) 1998 Acta Metallurgica Inc. Published by Els evier Science Ltd. All rights reserved.