Two-phase crystallization kinetics of Syndiotactic Polystyrene

In this work, a two phase crystallization model based on the extension of the Kolmogoroff approach was proposed and verified by comparison with experimental isothermal and nonisothermal crystallization data of Syndiotactic Polystyrene (sPS) in a very wide range of cooling rates, up to 600 °C/s. To investigate the effects of high cooling rate on the sPS crystalline structure, a homemade apparatus was adopted. The morphology in solid samples was analyzed by densitometry, IR spectroscopy, and X-rays diffraction. The coupling of these techniques allows the determination of the fractions of different crystalline phases. In agreement with melt-crystallization studies of sPS proposed by different authors, either a and ? forms could be produced depending on the thermal history of the sample. Results show that the stable ? form is favored for specimens solidified at higher temperature or under low cooling rates, whereas a and mesomorphic forms are favoured at low temperature or high cooling rates. The proposed multiphase crystallization kinetics model successfully described all the range of experimental data.