高保坍型聚羧酸减水剂的制备及其在水溶液中的自组装行为

Preparation and Self⁃assembly Behavior of High Slump⁃retention Type Polycarboxylates Water⁃reducing Admixture

采用自由基聚合原理制备了一种高保坍聚羧酸减水剂,研究了酸醚比、引发剂双氧水用量、链转移剂用量、反应温度及具有不同水解速率的酯基聚合单体对保坍性能的影响。采用Material Stuido软件中的耗散动力学(DPD)探究其在水溶液中的自组装状态。结果表明:最佳制备工艺为:酸醚比2.0,酯醚比6.0,双氧水用量占聚醚单体质量的1.4%,链转移剂占聚醚单体质量1.1%,丙烯酸羟乙酯和丙烯酸羟丙酯复合使用,其中丙烯酸羟丙酯占总酯量的60%,反应温度为50℃。DPD模拟结果表示,合成的高保坍聚羧酸减水剂在水中具有高度卷曲状态,趋于球状。采用上述工艺制备的高保坍聚羧酸减水剂应用于混凝土中,在30℃条件下,保坍时长能够达到4 h。

High slump-retention type polycarboxylates water-reducing admixture (PCE)was prepared by free radical polymerization principle.Study onthe effects of the acid/ether ratio,the amount of hydrogen peroxide in initiator,the amount of chain transfer agent,the reaction temperatureand the ester monomer with different hydrolysis rate on the slump protection performance.Dissipation kinetics (DPD) of Material Stuido software was used to investigate the PCE self-assembly state in aqueous solution.The results show that the optimal preparation process as follows:acid/ether ratio 2.0,ester/ether ratio 6.0,H_(2)O_(2) content 1.4%,chain transfer agent 1.1%,hydroxyethyl acrylate and hydroxyl propyl acrylate were used in combination,which hydroxyl propyl acrylate accounted for 60%of the total amount of the monomer,the reaction temperature is 50℃.The results of DPD simulation show that the PCE has a highly curling state in water and tends to be globularl.The high slump-retention type PCE is applied to concrete which is prepared by the above technology,the slump-retention time can achieve 4 h at 30℃.