Dynamic Viscoelasticity of Poly(butylene terephthalate) during Isothermal Crystallization
Wataru KINOSHITA, Hisahiko KASHIHARA, Kenji URAYAMA and Toshikazu TAKIGAWA
Abstract:The dynamic viscoelastic behavior during isothermal crystallization of poly(butylene terephthalate) (PBT) has been investigated as a function of crystallization temperature (Tc). The enthalpy of crystal formation during the isothermal crystallization is also examined by differential scanning calorimetry (DSC). The equilibrium degree of crystallization in the long time limit is about 30%, almost independently of Tc. Correspondingly, the viscoelastic parameters at the equilibrium of crystallization are also independent of Tc. The crystallization rate decreases with increasing Tc, and the Tc dependence is well approximated by the Arrhenius type equation. The effect of crystallization on the viscoelasticity is considerably small in the initial stage of crystallization whereas it becomes pronounced in the later stage. Key Words:Poly(butylene terephthalate), Crystallization, Viscoelasticity