Surface-induced crystallization of syndiotactic polystyrene on high modulus carbon fibers

Abstract

Measurements have been made using a polarized optical microscope equipped with hot stages to investigate the surface-induced crystallization of syndiotactic polystyrene(s-PS) on high modulus(HM) carbon fibers. Both the induction times and crystal growth rates at various crystallization temperatures were measured. Based on the theory of heterogeneous nucleation, the interfacial free energy difference function Δσ of s-PS on HM carbon fibers was determined to be 0.61±0.02 erg/cm2. No difference in the crystal growth rate of s-PS has been found in either spherulites in the bulk or transcrystalline layers at the interface. From the morphology studies, it has been found that the thickness of the transcrystalline layer increases with crystallization temperatures, from 5 to 13 μm in the temperature range of 247–269°C. The efficiency of HM carbon fibers to induce the transcrystalline layer is found better in s-PS matrix than that in i-PP matrix based on the surface energies of the constituents. (Keywords: transcrystalline layer · syndiotactic polystyrene · high modulus carbon fibers)