催化剂对BHPT缩聚反应宏观动力学的影响

Effect of Catalysts on the Macrokinetics of BHPT Polycondensation

采用钛系催化剂和促进剂,研究了高真空(低于50Pa)、不同温度(240～276℃)条件下对苯二甲酸双羟丙酯(BHPT)缩聚形成聚对苯二甲酸丙二酯(PTT)表观反应动力学。研究发现在相同温度下,钛系催化剂和助催化剂复合体系催化的缩聚反应表观速率常数是钛系催化剂催化的1.5～2.4倍。当温度高于268℃时,PTT热降解反应导致缩聚反应表观速率常数降低。当温度低于260℃时,产物的特性粘度随时间增大;但温度高于260℃时,在200min内产物的特性粘度出现最大值。另外,助催化剂本身对BHPT缩聚无催化作用且对PTT热降解反应无影响。

Using titanium catalyst with and without a promoter respectively, the kinetics behavior of polycondensation of bihydroxyl propylene terephthalate (BHPT) to poly(trimethylene terephthalate) (PTT) was investigated in terms of PTT intrinsic viscosity under high vacuum (P less than or equal 50 Pa) and a temperature range of 240°C to 276°C. It was found that the apparent rate constant in case of titanium catalyst with a promoter was 1.5-2.4 times as high as that in the case of titanium catalyst alone. As the reaction temperature TR>268°C, the apparent rate constant of BHPT polycondensation gradually declined due to the thermal degradation of PTT. Over a 200 min period of reaction, the intrinsic viscosity of PTT increased with reaction time as TR less than or equal 260°C, whereas a maximum intrinsic viscosity occurred as TR>260°C. It was further observed that the promoter alone had no catalytic effects on both BHPT polycondensation and PTT degradation.