Non-Isothermal Crystallization Kinetics of Poly(Butylene Terephthalate)/Silica Nanocomposites

Poly(butylene terephthalate)/silica nanocomposites were prepared by in situ polymerization of terephthalic acid, 1,4-butanediol and silica. Transmission electron microscopy (TEM) was used to examine the quality of the dispersion of silica in the PBT matrix. The non-isothermal crystallization behavior of pure PBT and its nanocomposites was studied by differential scanning calorimetry (DSC). The results show that the crystallization peak temperatures of PBT/silica nanocomposites are higher than that of pure PBT at a given cooling rate. The values of halftime of crystallization indicate that silica could act as a heterogeneous nucleating agent in PBT crystallization and lead to an acceleration of crystallization. The non-isothermal crystallization data were analyzed with the Avrami, Ozawa, and Mo et al. models. The non-isothermal crystallization process of pure PBT and PBT/silica nanocomposites can be best described by the model developed by Mo et al. According to the Kissinger equation, the activation energies were found to be -217.1, -226.4, -259.2, and -260.2 kJ/mol for pure PBT and PBT/silica nanocomposites with silica weight content of 1, 3 and 5 wt%, respectively.