保坍型聚羧酸减水剂常温合成及性能研究

Research on normal temperature synthesis and properties of polycarboxylate superplasticizer with slump retention capability

采用异戊烯醇聚氧乙烯醚(TPEG)、丙烯酸(AA)、保坍功能单体(ZD1)、丙烯酸羟乙脂(HEA)四元共聚体系及链转移剂次磷酸钠(NaH_(2)PO_(2)),在双氧水(H_(2)O_(2))/抗坏血酸(Vc)/1%硫酸亚铁(FeSO_(4))氧化还原引发体系下,通过常温(20~25℃)自由基溶液聚合制备了一种保坍型聚羧酸减水剂(HY1)。探讨了反应温度、不饱和羧酸、保坍功能单体、氧化剂、还原剂等因素对合成减水剂HY1性能的影响。结果表明,HY1的最佳制备工艺为:m(TPEG)∶m(AA)∶m(ZD1)∶m(HEA)∶m(Vc)=100∶3∶18∶3∶0.12,H_(2)O_(2)、1%FeSO_(4)、NaH_(2)PO_(2)用量分别为大单体质量的1.2%、0.1%、1.5%。经试验验证,与市售保坍型减水剂(PCE-1)相比,HY1在初始分散性、分散保持性及混凝土3、7、28 d抗压强度增长方面都明显较优。

A slump-preserving polycarboxylate superplasticizer(HY1)was synthesized by free radical solution polymerization at room temperature(20~25℃).It used a four-element copolymerization system of isopentenolpolyoxyethylene ether(TPEG)/acrylic acid(AA)/slump preserving functional monomer(ZD1)/hydroxyethyl acrylate(HEA)in the redox initiation system of hydrogen peroxide(H_(2)O_(2))/ascorbic acid(Vc)/1%ferrous sulfate(1%FeSO_(4)).Among this system,sodium hypophosphite(NaH_(2)PO_(2))was used as chain transfer agent.The effects of reaction temperature,unsaturated carboxylic acid,slump preserving functional monomer,oxidant and reducing agent on the properties of slump preserving HY1 were discussed in this paper.The results showed that the optimal formula of HY1 was as follows:m(TPEG)∶m(AA)∶m(ZD1)∶m(HEA)∶m(Vc)=100∶3∶18∶3∶0.12,and the dosage of H_(2)O_(2),1%FeSO_(4) and NaH_(2)PO_(2) were 1.2%,0.1%and 1.5%of the mass of macromonomer respectively.Tests have verified that compared to a slump-preserving polycarboxylate superplasticizer(PCE-1)on sale in the domestic market,HY1's initial dispersion and retention performance and the strength growth of concrete in 3,7 and 28 d are significantly better.