4,4'/2,4'-二苯基甲烷二异氰酸酯/多元醇本体聚合流变动力学

采用转矩流变仪模拟双螺杆挤出反应条件,分别在无催化剂和铋/锌复合催化剂作用下进行4,4'/2,4'-二苯基甲烷二异氰酸酯/聚四氢呋喃醚二醇/1,4-丁二醇本体聚合,结合二维流动简化假设、黏度/分子量关联式和Arrhenius方程,建立了热塑性聚氨酯(TPU)重均分子量与反应体系转矩、温度的流变动力学方程,分别拟合得到无催化剂和催化剂作用时体系转矩与重均分子量的关联式;发现采用流变动力学方程模拟的TPU平均分子量与实时取样后采用凝胶渗透色谱法测定的结果吻合良好,采用流变动力学方法测量方便迅速,能提供整个反应过程中TPU平均分子量的变化情况。

Rheokinetics of 4,4'/2,4'-diphenylmethane diisocyanate/polyols bulk polymerization

Bulk polymerizations of 4,4'/2,4'-diphenylmethane diisocyanate/polytetramethylene ether glycol/1,4-butylene glycol without and with the addition of Bi/Zn composite catalyst were carried out to synthesize thermoplastic polyurethane (TPU) in a torque rheometry to simulate twin-screw extruder conditions, and the rheokinetics of polymerization process was investigated.The relations between torque and weight average molecular weight (M_W) of TPU were corrected based on two-dimensional flow simplification, correction between melt viscosity and molecular weight, and Arrhenius equation.The rheokinetics model was used to fit the variation of M_W of TPU during polymerization.The fitted M_W of TPU showed good agreement with that determined by gel permeation chromatography.The rheokinetic model could quickly provide real-time fitting results of M_W of TPU from the torque for the whole synthesis process.