Crystallization Kinetics for the Split Dual Phase Model of the Amorphous State of Polymers

We analyze constant rate cooling and heating crystallization kinetics of PET samples by DSC. The samples have various degrees of disentanglement, obtained by Rheo-Fluidification. According to the interactive Split Dual Phase model, the amorphous state is made up of two coupled and interactive amorphous phases. These two phases have distinct viscoelastic and thermodynamic characteristics (T_g, free volume, G′ and G^″, etc.), which are determined by the potential energy of the conformers and by the state of entanglement of the macromolecular coils. Semi-crystalline polymers, such as polyethylene terephthalate (PET), are amorphous in the molten state and should have Dual Phase behavior. The phase duality should manifest itself during crystallization from the melt during cooling, or during cold crystallization while heating quenched samples. The purpose of this communication is to quantitatively describe the kinetics of crystallization of PET samples with a dual phase kinetics formulation, and determine the respective influence of molecular weight and degree of entanglement on the kinetics parameters, rate of crystallization and percentage of crystallinity.