柠檬酸改性聚羧酸减水剂的合成

以2-丙烯酰氧基-1,2,3-三羧基丙烷(ACP)、丙烯酸(AA)、丙烯酸聚乙二醇单甲醚酯(MPA)和甲基丙烯磺酸钠(MAS)为单体,过硫酸铵(APS)为引发剂,采用水溶液共聚法合成柠檬酸改性四元聚羧酸系减水剂。实验结果表明,改性聚羧酸减水剂的最优合成条件为:反应温度90℃,反应时间5 h,APS用量为单体总质量的2.5%,在单体配比为n(ACP)∶n(AA)∶n(MPA)∶n(MAS)=0.47∶3.5∶1.2∶1.0,所合成减水剂的减水率高达31%,2 h内水泥净浆流动度基本无损失。

The synthesis of polycarboxylate superplasticizer modified by citric acid

A novel polycarboxylate superplasticizer modified by 2-hydroxy-1,2,3-propanetricarboxylic acid was prepared.The superplasticizer was directly polymerized using 2-acryloyloxy-1,2,3-tricarboxylic propane(ACP),acrylic acid(AA),methoxypolyethylene glycol acrylate(MPA),and sodium methylallyl sulfonate(MAS) with ammonium persulfate as initiator in aqueous media.The results showed that the optimum reaction condition are as follows:the molar ratio of ACP to AA to MPA to MAS is 0.47∶3.5∶1.2∶1.0,the dosage of ammonium persulfate is 2.5% of total monomers by mass,the reaction temperature is 90 ℃ and the reaction time is 5 h.The polycarboxylate superplasticizer prepared under this condition would have good plasticizing and fluidity.The water-reducing ratio for SPC is 31%,the fluidity of cement paste almost remained constant in 2 h.