TRANSCRYSTALLIZED INTERPHASE IN THERMOPLASTIC COMPOSITES .2. INFLUENCE OF INTERFACIAL STRESS, COOLING RATE, FIBER PROPERTIES AND POLYMER MOLECULAR-WEIGHT

Application of stress at the interface between a fibre and a supercooled polymer melt results in the growth of a transcrystallized interphase, independent of fibre type and crystallization temperature. This is in direct contrast to results obtained from quiescent crystallization, where the occurrence of transcrystallization does depend on fibre type and crystallization temperature. The observed relation between stress-induced nucleation and transcrystallization leads us to propose that the origin of transcrystallization is actually stress-induced nucleation, due to the stresses caused by cooling two materials with a large difference in thermal expansion coefficient. In support of this, we present results showing that transcrystallization is dependent on the axial thermal expansion coefficient of the fibre, the sample cooling rate, the fibre length, the position along the fibre, and the polymer molecular weight.