Effects of Nanosilica on Crystallization and Thermal Ageing Behaviors of Polyethylene Terephthalate

摘要

The effects of nanosilica(Si O2) on crystallization and thermal aging behaviors of polyethylene terephthalate(PET) have been studied using differential scanning calorimetry(DSC) and polarized optical microscopy(POM), viscometry, tensile testing and scanning electron microscopy(SEM). For non-isothermal and isothermal crystallizations, the crystallization rate of PET increases considerably with increasing content of Si O2 providing a large number of nucleation sites, but the relative crystallinity of the nanocomposites has little differences with that of neat PET. According to POM observation, the nucleation of PET becomes faster and the nucleation density increases significantly with increasing Si O2 content. For PET and its nanocomposites thermally aged at 190 °C, the results of intrinsic viscosity, carboxyl content and tensile test show that the degradation rate of PET is reduced with the addition of a small content of Si O2, but the degradation rate increases with further addition of Si O2, owing to the dual effect of Si O2 on PET degradation.