Abstract:

In order to prepare stable and highly active titanium catalyst, a series of titanium silicon (Ti-Si) composite catalysts were prepared and the best catalyst was selected. By employing this catalyst in preparation of polyethylene glycol terephthalate (PET), the influence of catalysts dosage and polycondensation temeffect temperature on polymerization reaction and the properties of polyester chips were investigated. In addition, kinetics for polymerization was studied. Polymerization results were also compared with classical antimony catalyst (Sb2O3) and titanium catalyst (Ti(X)). Results show that the optimized dosage of catalyst is 19 μg/g and the suitable polycondensation temperature is 281℃ under the testing condition. Ti-Si catalyst played an effective role both in esterification and polycondensation. Ti-Si catalyst has much lower esterification activation energy which is only 42.49 kJ/mol, and it accelerated the esterification reaction. The polycondensation time by Ti-Si is much shorter (40min) than other catalysts Sb2O3 and Ti(X). The kinetic data for polycondensation demonstrated that the condensation activation energy by Ti-Si is similar to Ti(X), but lower than Sb2O3. The resultant PET chips by Ti-Si catalyst has similar thermal and mechanical properties with those by Ti(X), but better than those by Sb2O3. In addition, the chips by Ti-Si possessed brighter chroma than those by Sb2O3, and have the similar b value with Ti(X).

Key words: polyethylene glycol terehthalate, titanium catalyst, esterification, polycondensation, reaction kinetics