FTIR法研究催化剂对聚氨酯脲固化过程的催化作用

Study of Catalyst Effect on the PUU Cure Kinetics by Using FTIR

用傅立叶变换红外光谱仪 ( FTIR)“原位”研究了聚氨酯脲固化过程中催化剂三乙烯二胺 ( DABCO)和二月桂酸二丁基锡 ( DBTDL)的催化作用。结果表明 :本体聚合反应中 ,在低转化率下 ,反应规律表现为良好的二级动力学关系 ,给出了反应初期的动力学常数 ;反应后期高转化率时 ,低温下反应受扩散控制影响 ,NCO和 NH2 反应的二级反应动力学速率常数逐渐变小 ,而高温下 ,逐渐升高 ;非催化下 NCO与 NH2 反应的活化能为2 6.4k J· mol- 1,而 DBTDL存在下活化能无变化 ( 2 6.5 k J· mol- 1) ,所以 DBTDL对该反应无催化作用。加入 DABCO后 ,NCO与 NH2 的反应活化能为 1 3.5 k J· mol- 1。

The kinetic studies of curing reaction of PUU catalyzed by DABCO and DBTDL were studied by using in-situ quantitative FTIR. It showed that the reactions, uncatalyzed and catalyzed by dibutyltin dilaurate(DBTDL),followed 2nd-order kinetics at low conversion rate.At high conversion rate, the 2nd-order constants at lower temperature decreased with increasing reaction time due to the influence of diffusion control. However, they increased with increasing reaction time at higher temperature.According to the kinetics curves at low conversion rate, the Ea of the uncatalyzed bulk polymerization is 26.4 kJ·mol -1.With addition of catalyst DBTDL,the Ea of the reaction almost keeps the constant (26.5 kJ·mol -1),so DBTDL has no catalytic effect on the reaction of NCO with NH 2.With addition of DABCO,the Ea of the reaction of NCO with NH 2 is 13.5 kJ·mol -1.