基于光引发剂分解动力学调控聚合过程的研究

Polymerization Process Regulation Based on Photoinitiator Decomposition Kinetics

通过采取定期取样的办法,利用紫外分光光度仪测得不同时间下的同一时刻的丙烯酰胺的转化率和光引发剂2-羟基-2-甲基-1-[4-(2-羟基乙氧基)苯基]-1-丙酮在混合物中的含量,可以发现丙烯酰胺的光聚合过程存在明显的3个阶段,根据同一时刻下丙烯酰胺的转化率对应的引发剂的含量,建立以光引发剂消耗量划分聚合过程的三阶段模型,将聚合过程分为聚合前期、聚合中期和聚合后期,通过光照强度、狭缝宽度和旋转速度研究了光引发剂的分解动力学,计算出不同条件下的引发剂的分解速率常数kd.结果表明,实验条件下光引发剂分解速率常数kd在4.00×10^(-4)s^(-1)内可调控,在聚合三阶段模型中存在最佳kd组合,即第一阶段kd为4.00×10^(-4)s^(-1),第二阶段kd为1.90×10^(-4)s^(-1),第三阶段kd为1.90×10^(-4)s^(-1),得到合成聚丙烯酰胺(PAM)的最佳自由基浓度是10.82×10^(-8)~12.56×10^(-8)mol·L^(-1)s^(-1),光引发剂的初始浓度[I]0应控制在100~110 mg/L.

By using the periodically sampling approach and UV spectrophotometry the conversion of acrylamide and the content of the photoinitiator 2-hydroxy-2-methyl-1-[ 4-（2-hydroxyeth-oxy） phenyl ]-1- acetone in the polymerization process were measured. There are three stages in the photo-polymerization process of acrylanide, according to the acrylamide conversion rate and the corresponding initiator content. A three-stage model of polymerization process was established by the photoinitiator consumption, and the polymerization process was divided into the initial period of polymerization, the polymerization period and the later period of polymerization. The decomposition kinetics of photoinitiator was investigated with a homemade photopolymerization instrument. The initiator decomposition rate constant （kd） was calculated under different conditions. The results show that, photoinitiator decomposition rate constants kd within 4.00×10^-4s^-1 can be regulated under the experimental conditions,and there is a best kd combination in the three-stage model,that is,thekdofafirst stage was 4.00×10^-4s^-1,thekdofthe second stage was 1.90 4.00×10^-4s^-1,thekdofthe third stage was 1.90 4.00×10^-4s^-1. The optimal free radicals concentration of synthesis of polyacrylamide （PAM） is 10.82×10^-8～12.56×10^-8mol·L^-1s^-1. Photoinitiator initial concentration [ I]0 should be controlled at 100- 110 mg/L.