Study On The Crystalline Properties Of Nano Zinc Oxide Modified Polyster

PET, PTT and PBT are the principal members of the commerciallized polyesters. One important research field in modified polyesters is the preparation of modified polyesters by using these three kinds of polyesters through physical and chemical methods. Although China has become the world’s largest polyester producer, the probloms of expanding the application field of polyester products further and enhancing its value-added products were still needed to be treated in the future. Nano- zinc oxide has been used in modified polymers owing to its small size effects, surface effects and good dispersion properties. In this paper, terephthalic acid(PTA), ethylene glycol(EG), 1, 3-propanediol(PDO), 1, 4-butanediol(BDO) have used as raw materials to synthesize PET、PTT、PBT and their nano/ZnO nanocomposites by adding self-made nano-ZnO using a 5L polycondensation reactor through in situ polymerization, we also discussed the crystallization behavior of the modified polyesters.Ubbelohde viscometer was used to analysis and determine their intrinsic viscosity and viscosity-average molecular weight; differential scanning calorimetry(DSC) and hot stage polarizing microscopewas were used respectively to analyze the crystallization behavior and crystalline morphology of modified polyester, Avrami equation was used to analyze the isothermal crystallization kinetics. The non-isothermal crystalline properties were characterized by using Jeziorny method, Ozawa and Mo methods to explore the influence of the cooling rate on crystal properties of the modified polyester.The results showed that the polymerization process did not need to be changed when small amounts of nano zinc oxide were used in the polymerization for these three kinds of polyesters. The photos of POM showed that the crystal morphology of nanocomposites were different with the addition of nano-zinc oxide. Isothermal crystallization kinetics results showed that nano ZnO can make nanocomposites nucleation rate much higher than that of pure polysters and accelerate the crystallization rate, indicating an obvious heterogeneous nucleation by adding a small amount of nano-ZnO. Nonisothermal crystallization kinetics study confirmed that Jeziorny and Mo methods could be applied to analyze the nonisothermal crystallization process better. In addition, it showed that nano-ZnO could play a good role in promoting crystallization properties for all nanocomposites; however, Ozawa method is not suitable for description of crystallization kinetics of modified polyester because of the poor linear relationship of the data.