以4-羟丁基乙烯基聚氧乙烯醚(VPEG)大单体、丙烯酸(AA)为主要原料，引入保坍单体丙烯酸羟乙酯(HEA)，以巯基丙酸(MPA)为链转移剂，在H2O2/L-抗坏血酸(VC)氧化还原引发体系下，通过自由基聚合制备出减水保坍型聚羧酸减水剂(V-HEA)。通过红外光谱、凝胶色谱测试对合成的V-HEA进行分子结构表征，并与市售保坍型聚羧酸减水剂(HPWR-S)进行水化热与混凝土性能对比分析。结果表明，V-HEA的最佳合成工艺参数为酸醚比4。4，酯醚比2。5，引发剂、硫酸亚铁和链转移剂掺量分别占大单体质量的0。76％、0。10％和0。74％。掺入硫酸亚铁可提高单体的转化率，且V-HEA的数均分子量为17 650，重均分子量为42 713，单体转化率高达95。03％。掺入V-HEA时混凝土的水化峰值温度较掺入HPWR-S时延迟4 h 24 min，且第二水化速率峰出现时间延迟约4 h，更加延缓水泥的水化。掺入V-HEA的混凝土 2 h坍落度仅损失5。8％，且混凝土强度与掺入HPWR-S产品相当，V-HEA具有较好的应用前景。
Synthesis and Properties of Water-Reducing and Slump-Protecting Polycarboxylate Superplasticizer
The water-reducing and slump-protecting polycarboxylate superplasticizer(V-HEA)was prepared by free-radical polymerization with 4-hydroxybutyl vinyl polyoxyethylene ether(VPEG)macromonomer and acrylic acid(AA)as the main raw materials by adding the slump-preserving monomer hydroxyethyl acrylate(HEA),and mercapto-propionic acid(MPA)as chain transferr agent under the H2 O2/L-vitamin C(Vc)oxidation-reductioninitiator system.The synthesized V-HEA was characterized by infrared spectroscopy,gel chromatography testing,and it was subjected to hydration heat analysis and concrete performance comparison analysis with commercially available slump-preserving polycarboxylate superplasticizer(HPWR-S).The results show that the optimal synthesis process parameters of V-HEA are acid-ether ratio of 4.4,ester-ether ratio of 2.5,and the dosage of initiator,ferrous sulfate and chain transfer agent accounted for 0.76％,0.10％and 0.74％of the mass of the macromonomer,respectively.The incorporation of ferrous sulfate could improve the conversion rate of monomers,and the number average molecular weight of V-HEA is 17 650,the weight average molecular weight is 42 713,and the conversion rate of monomers is as high as 95.03％.The peak temperature of hydration reaches by the incorporation of V-HEA is delayed by 4 h 24 min compared with HPWR-S,and the occurrence time of the second hydration rate peak is delayed by about 4 h,which further delays the hydration of cement.In comparison test of concrete performance,the 2 h slump only decreases by 5.8％with the addition of V-HEA,and the strength of concrete is comparable to that of HPWR-S products,so V-HEA has good application prospects.
国家科技期刊平台
NSTL
万方数据
维普
