CRYSTALLIZATION KINETICS IN MIXTURES OF POLY(EPSILON-CAPROLACTONE) AND POLY(STYRENE-CO-ACRYLONITRILE)

Isothermal crystallization kinetics in the miscible mixtures of poly(e psilon-caprolactone) (PCL) and poly(styrene-co-acrylonitrile) (SAN) ha ve been investigated as a function of the composition and the crystall ization temperature by optical microscopy. The radial growth rates of the spherulites have been described by a kinetic equation including th e interaction parameter and the free energy for the formation of secon dary crystal nuclei. Fold surface free energies decrease slightly with the increase of SAN content. The experimental findings show that the influence of the glass transition temperature of the mixture, which is related to the chain mobility, on the rate of crystallization predomi nates over the influence of the surface free energies. This indicates that the glass transition temperature of the mixture should be of more importance, so that the growth rates decrease when the content of the noncrystallizable component increases. In addition, the Flory-Huggins interaction parameter obtained by fitting the kinetic equation with e xperimental data is questionable.