多元复合引发体系常温合成高减水型聚羧酸减水剂研究

Research on synthesis of a high water-reducing type polycarboxylate superplasticizer by the multivariate composite initiation system at room temperature

以异丁烯醇聚氧乙烯醚(HPEG)、丙烯酸(AA)、马来酸二甲酯(DMM)为主要单体,通过引发体系对比,选取双氧水(H_2O_2)-过硫酸铵(APS)/维生素C(VC)-硫代硫酸钠(Na_2S_2O_3)为多元复合引发体系,采用水溶液自由基聚合,常温制备了一种高减水型聚羧酸减水剂(PCE)。通过正交试验,得出合成最佳工艺条件为:氧化剂和还原剂质量比为5.5,酸醚比为4.25,链转移剂用量为大单体质量的0.5%,初始反应温度25℃,滴加时间2 h,酯醚比为0.3。混凝土试验表明,当减水剂折固掺量为0.12%时,减水率达34.5%,与其他减水剂相比具有更好的分散性和分散保持性能。

A high water-reducing type polycarboxylate superplasticizer(PCE) was synthesized at room temperature with isobutylene alcohol polyoxyethylene ether(HPEG),acrylic acid(AA),and dimethyl maleate(DMM) as the main monomers. By the comparison of the initiating system,using hydrogen peroxide(H2O2)-ammonium persulfate(APS) and vitamin C(VC)-sodium thiosulfate(Na2S2O3) as the multivariate compound initiator system,using the aqueous solution of free radical polymerization. Through or- thogonal experiment,the optimum synthesis condition was that initial reaction temperature was 25 ℃,the quality ratio of oxidant and reductant was 5.5,the mole ratio of acid/ether 4.25,the amount of chain transfer agent was 0.5% the mass of HPEG,and the titration time was 2 h,the mole ratio of ester/ether was 0.3. The results of the concrete test showed that the water-reducing rate reached 34.5% when the dosage of the polycarboxylate superplasticizer was 0.12%,which was better dispersing performance and dispersed retention than other superplasticizer products.