SOLIDIFICATION OF SEMICRYSTALLINE POLYMERS USING A VARIABLE INTERFACETEMPERATURE MODEL

Solidification of semicrystalline materials often occurs in significan tly undercooled melts. The crystal growth process in such melts is con voluted due to the fact that the interface between the solid and liqui d domains of the microscopic crystals is at an unknown temperature. Ho wever, it is possible to let the temperature of this interface be unsp ecified and solve the problem with a semianalytical method if the grow th velocity is prescribed. Solutions for the temperature profiles in b oth solid and liquid phases are presented in this work, along with the interface temperature, for phase change processes controlled by the k inetics of crystallization rather than diffusion processes, which is t ypical for polymers. The method is used for one-dimensional problems i n cartesian, cylindrical, and spherical geometries that correspond to commonly found microstructures. It is found that the temperature of th e interface is significantly below the equilibrium melting point and a quasi steady-state regime is reached rapidly. Comparison with the cla ssical Neumann's solution shows that the temperature profiles are simi lar but the position of the interface differs considerably. (C) 1996 J ohn Wiley & Sons, Inc.