聚合-水解反应制备超高减水型聚羧酸减水剂

Preparation of polycarboxylic acid superplasticizers of high water reducing ratio by polymerization-hydrolysis reaction

以甲基烯丙醇聚醚、丙烯酸和丙烯酸羟乙酯为主要原材料,采用先共聚后水解的方法,合成了一系列聚羧酸减水剂,考察了不同羧基比例、不同酯基比例以及水解时间对减水剂分散性的影响。当n(MAPEG2400)∶n(AA)∶n(HEA)=1∶4∶2,pH值为13条件下水解30min时,合成的减水剂具有较高的水泥净浆分散性。当减水剂折固掺量为0.12%时,混凝土减水率达到40%,28d抗压强度比为142%。利用先聚合后水解的方法,实现了较高羧基含量减水剂的制备,为超高减水型聚羧酸减水剂产品的制备提供了新的方法。

A series of polycarboxylic acid superplasticizers（PCA） were synthesized from methyl allyl polyethylene glycol（MAPEG2400）,acrylic acid（AA）and 2-hydroxyethyl acrylate（HEA）by a route of hydrolysis after radical copolymerization. The effects of carboxyl group ratio,ester group ratio and time of hydrolysis on the properties of cement paste were systematically investigated. With a molar ratio of MAPEG2400,AA and HEA of 1∶4∶2,after a polymerization with a subsequent 30-min-hydrolysis（pH=13）process,the best flowability of cement paste would be achieved. At the dosage of 0.12 wt%,the water reducing ratio was 40% and the compressive strength ratio at 28 d was 142%. By the copolymerization and hydrolysis strategy reported herein,PCA with high carboxyl group content could be easily prepared. The new strategy is helpful for the synthesis of PCA products of high water reducing ratio.