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采用丙烯酸羟乙酯与酒石酸进行酯化,将酯化产物(M)与丙烯酸(AA)、甲基烯丙基聚氧乙烯醚(TPEG)、2-丙烯酰胺-2-甲基丙烷磺酸(AMPS)在引发剂过硫酸铵作用下进行共聚,合成了一种缓释型聚羧酸系减水剂。探讨了单体摩尔比、催化剂用量、酯化温度、带水剂等因素对酯化反应的影响,考察了酯化产物M对丙烯酸AA替代量对水泥净浆流动性的影响。结果表明:酯化反应的最佳条件为:n(酒石酸)∶n(丙烯酸羟乙酯)=1∶5,酯化温度85℃,催化剂对甲苯磺酸掺量3%,带水剂环己烷用量为反应物总质量的40%;将合成的酯化产物M部分替代AA进行减水剂的合成,最佳单体比例为:n(AA)∶n(TPEG)∶n(AMPS)∶n(酯化产物M)=1.25∶1.00∶0.27∶2.00;当合成的聚羧酸减水剂掺量为0.3%时,水泥净浆初始流动度为245.0 mm、1 h流动度为207.5 mm、2 h流动度为225.0 mm,制备的聚羧酸减水剂具有良好的缓释功能。
Esterification of esterified product (M) with acrylic acid (AA), methylallyl polyoxyethylene ether (TPEG), 2-acrylamido-2-methylpropane sulfonic acid AMPS) under the action of initiator ammonium persulfate to synthesize a kind of sustained-release polycarboxylate superplasticizer. The influences of monomer molar ratio, catalyst amount, esterification temperature and water-entraining agent on the esterification reaction were investigated. The effect of esterification product M on the liquidity of cement paste was investigated. The results showed that the optimal conditions for the esterification reaction were n (tartaric acid): n (hydroxyethyl acrylate) = 1: 5, esterification temperature 85 ℃, catalyst p-toluenesulfonic acid content 3% The amount of alkyl was 40% of the total mass of the reactants; the synthesis of the superplasticizer was carried out by substituting part M of the synthesized esterified product with AA. The optimum monomer ratio was n (AA): n (TPEG): n (AMPS) (esterification product M) = 1.25:1.00:0.27:2.00. When the amount of synthesized polycarboxylate superplasticizer is 0.3%, the initial fluidity of cement paste is 245.0 mm, the fluidity of 1 h is 207.5 mm, 2 h, the flowability of 225.0 mm, prepared polycarboxylate superplasticizer has a good slow release function.