Thermal behavior of poly (ethylene terephthalate)/SiO2/TiO2 nano composites prepared via in situ polymerization

The PET/SiO2/TiO2 composites were prepared via in situ polymerization. The effect of nano SiO2 and TiO2 content on crystallization behavior and thermal stability of PET was investigated by differential scanning calorimeter (DSC), X-ray diffraction (XRD), and thermogravimetry. The morphology of SiO2 and TiO2 particles and their dispersion in PET were studied by scanning electron microscope. The addition of SiO2 and TiO2 nano particles affects the thermal stability and flame property of PET and the effect depends on their content. It also affects the perfect degree of PET crystal. From DSC data analysis, crystallization temperature and enthalpy value reduce with SiO2 and TiO2 nano particles, but they increase with increasing SiO2 and TiO2 loading. A low content of SiO2 and TiO2 nano particles will decrease the degree of crystallinity, but enough amounts of them will increase the degree of crystallinity of PET because of heterogeneous nucleating effect of the particles. The degree of crystallinity calculated based on XRD data also shows this phenomenon. From XRD results analysis, it is also found that the average grain size of PET decreases with a little of SiO2 and TiO2 nano particles, but it increases with increasing content of particles.