无水聚羧酸减水剂的热引发聚合历程及性能

The thermal-initiation polymerization process and performance of water-free polycarboxylate superplasticizers

采用不同引发剂制备了3种无水聚羧酸减水剂,通过GPC分析深入研究了聚合过程的分子质量及分子质量分布、聚醚转化率、酸醚比分布趋势,并通过净浆流动度和混凝土性能评价试验表征了减水剂的性能。结果表明:采用AIBN和APS引发剂合成的减水剂分子质量及其分布随时间逐渐增大,而采用AIBN/APS复合引发的减水剂则呈先增大后减小再增大的现象,在聚合初期表现出明显的协同增强效果。AIBN和APS复合使用具有更好的引发效率、更高的聚醚单体转化率、更均匀的实际酸醚比和区间酸醚比分布范围,合成减水剂的分散性能最佳。

In this paper, three kinds of water-free polycarboxylate superplasticizers were prepared by different initiators. Using GPC method,the molecular weight and its distribution of polymerization process,the conversion rate of polyether and the distribution trend of acid-polyether ratio were studied. The properties of polymer were characterized by the flowability of cement paste and the workability of concrete. The experimental results show that the molecular weight and its distribution of AIBN and APS gradually increased over time,while AIBN/APS increases first and then decreases and then increases. It showed that the synergistic enhancement effect of initiators at the beginning of polymerization obviously. The composite use of AIBN and APS has better excitation effect,higher conversion rate of polyether monomer, more uniform acid ether ratio and acid ether ratio distribntion;It showed the best dispersing performance.