CRYSTALLIZATION AND MELT BEHAVIOR OF ISOTACTIC POLY((4-ALPHA,ALPHA-DIMETHYL-BENZYL)PHENYL METHACRYLATE)

The crystallization and melting behaviour of practically 100% isotacti c poly((4-alpha,alpha-dimethylbenzyl) phenyl methacrylate) has been st udied by d.s.c. and light microscopy. Crystallization from the melt se emed to be non-spherulitic. The maximum crystallization rate, which co uld only be determined by d.s.c., was found to be 2% min(-1) at a crys tallization temperature T of 155 degrees C. Assuming that the growth r ate theory for small supercooling is valid and by taking the appropria te value 51.6K for the constant c(2) of the WFL equation, the chain-fo lded surface free energy sigma(e) was estimated at 89 x 10(-2) J m(-2) . The melting curves showed two melting endotherms. Crystallization fr om the melt produced a small melting endotherm just above T,. This pea k may originate from secondary crystallization of tie molecules melt t rapped within the crystalline phase. The peak temperature of the secon d melting endotherm increased linearly with T-c, yielding an extrapola ted value for the equilibrium melting temperature T-m(0) of 282 degree s C. Avrami analysis showed for the exponent n noninteger values betwe en 2 and 3, indicating at least a non-spherulitic growth process which is confirmed by the 'rod-like' morphology of the crystalline phase as determined by phase-contrast light microscopy. (C) 1997 Elsevier Scie nce Ltd.