Kinetics of melting and characterization of the thermodynamic and kinetic properties of syndiotactic polystyrene

A study of the crystallization process of syndiotactic polystyrene is carried out, with particular emphasis on the effect of previous melt annealing on the subsequent crystallization kinetics and polymorphism, with a combination of thermal analysis, infrared spectroscopy, and X-ray diffraction. An effort is made to obtain quantitative results in terms of the relative crystallinity content of the alpha and beta phases after a given thermal treatment. A kinetics of melting for the crystalline memory is proposed, which enables the determination of the time at a given temperature that ensures the complete fusion of the a crystals. This leads to a generalization of the effects of the time-temperature couple on the memory effect. A particular protocol is identified, which upon solidification from the melt induces the development of just one crystalline phase, either alpha or beta. This allows the determination of the enthalpy of crystallization, the maximum attainable crystal volume fraction, the crystallization half-time as a function of temperature, and the Avrami index for each of the two crystalline phases.