Research On The Environmental-friendly Poly(Trimethylene Terephthalate)-PTT

In this paper, PTT（Poly trimethylene terephthalate）with different viscosity（molecular weight） were synthesised using PTA（pure terephthalic acid） and1,3-PDO（1,3-propanediol） as the substrates and the type of Ti（Ⅳ） and Sb（Ⅲ）ascatalysts by the way of direct esterification--prepolycondensation--finalpolycondensation. We discussed the influence of different factors such as the ratio ofsubstrates,the amount of catalysts, the temperature of polycondensation and the timeof polycondensation. We got the optimal reaction conditions： the ratio of the alcoholto the acid （1,3-PDO/PTA）1.7:1, the amount of catalysts Sb2O31000ppm of PTA、Ti（OC4H9）4800ppm of PTA, the temperature of polycondensation255℃and thetime of polycondensation3h. In this period of experiment, PTT with the viscosity0.83dL/g has been synthesised. And comparing with references now available, thisviscosity （molecular weight） is better than the majority.Also, antimony（Ⅲ）1,3-propanediolate was synthesised as a new kind of catalyst for polycondensationsuccessfully.The product is proved to be the target molecule by the mass fraction ofantimony, the¹H NMR spectra and the¹³C NMR spectra.The viscosity0.68dL/g ofPTT has been synthesised under the conditions we have used, with both antimony（Ⅲ）1,3-propanediolate and Nano-TiO2as catalysts.Also,we attempted to add propanetriolinto PTT in order to get a high-performance PTT. Under the conditions we have used,propanetriol interesterificated during the period of prepolycondensation.When themass fraction of propanetriol is0.5percentage,the viscosity can be as good as0.86dL/g.