聚氨酯丙烯酸酯光固化反应动力学的研究

用光DSC (DPC)考察了三种聚氨酯丙烯酸酯 (PUA)预聚物 ,即传统的、扩链的以及接枝的PUA的光固化动力学行为。讨论了不同的反应条件对三种PUA的光固化动力学的影响。利用DPC数据计算出反应速率与各种影响因素的指数关系。预聚物的引发剂指数均小于 0 5。对于传统的和扩链的PUA ,光强指数稍低于0 5 ,单体浓度指数近似于 1,而对于接枝PUA则分别为 0 5 6～ 0 6 8和 1 2 5。在恒定光强和引发速率条件下反应速率与转化率的关系算出kp/kt1/ 2 ,在非稳态条件下反应速率对时间的关系算出kt/kp,可以求出kp 和kt 值。结果表明 ,体系的凝胶效应使kp 和kt 随转化率增加而大大下降

STUDIES ON THE PHOTOCURING KINETICS OF POLYURETHANE-ACRYLATES

The curing kinetics was found to be affected by various factors，such as photoinitiator concentration and incident light intensity.The power dependence of reaction rate on various parameters had been determined from DPC data.The exponent of initiator concentration for all the prepolymers was found to be less than 0.5.For conventional and chain-extended PUA，the exponent of incident light intensity was slightly less than 0.5 and that of monomer concentration was close to unity，compared with grafted PUA，it was 0.56～0.68 and 1.25 respectively.The ratio k\-p/k\-t1/2 was calculated from rate vs.conversion data under constant irradiation.while the ratio k\-p/k\-t was obtained from the analysis of rate vs.time data under non-steady state.Consequently，the k\-p and k\-t could be individually calculated.Both k\-p and k\-t were found to substantially decrease with couversion due to the gelation of the sticky system.