论文部分内容阅读
合成了一系列不同分子量的聚己内酯 ,进而制备异氰酸根封端的聚己内酯预聚体 ,用傅里叶变换红外光谱研究了不同分子量的聚己内酯预聚体与二元醇的扩链反应 .扩链反应动力学研究结果表明 :聚己内酯预聚体与二元醇的扩链反应均为二级反应 ;随着软链段反应物料分子量的增加 ,反应速率常数显著降低 ,但当分子量超过某一范围后 ,其对反应速率的影响逐渐减小 ,趋于不变 .对于不同硬链段反应物料含量的扩链反应体系 ,硬链段反应物料含量越高 ,软链段反应物料分子量对反应速率的影响越明显 ,而且 ,当软链段反应物料分子量超过某一范围后 ,不同体系的反应速率常数间的差值趋于不变 .Arrhenius方程中的指前因子 ( B)随软链段反应物料分子量的变化关系与速率常数对分子量的依赖关系相同 ;从反应速率常数对温度的依赖关系可见 :表观活化能的直线斜率基本相同 ,扩链反应的活化能主要与官能团的反应活性相关
A series of polycaprolactones with different molecular weights were synthesized to prepare isocyanato-capped polycaprolactone prepolymer. The effects of polycaprolactone prepolymers with different molecular weights and diols The results of the chain extension reaction kinetics show that the chain extension reaction of the polycaprolactone prepolymer and the diol are both secondary reactions and the reaction rate constant is significant as the molecular weight of the soft segment reaction material increases But when the molecular weight exceeds a certain range, its influence on the reaction rate gradually decreases and tends to be invariable.For the chain reaction system with different content of hard segment reaction, the higher the content of hard segment reaction material, the softer The more obvious the influence of molecular weight on the reaction rate is, and the difference between the reaction rate constants of different systems tend to be constant when the molecular weight of the soft segment reaction material exceeds a certain range.The pre-exponential factor in the Arrhenius equation (B) The molecular weight dependence of the rate constant on the reaction of the soft segment is the same as that of the rate constant. From the dependence of the reaction rate constant on the temperature, the linear slope of the apparent activation energy Substantially the same, the main chain extension reaction activation energy associated with reactive functional groups