Xiaodi Du;Hui Li;Jiaheng Lei;Anfu Zhang;
<正>Ester based polycarboxylate superplasticizers were synthesized using acrylic acid and polyethylene glycol as raw material.The influence of diester content in esterification products of acrylic acid and polyethylene glycol on the performance of polycarboxylate superplasticizer was studied by reversed-phase high performance liquid chromatography.Results showed that,both polyethylene glycol mono-acrylate and di-acrylate existed in estrification product and the content of di- and mono-acrylate only depended on esterification ratio of acrylic acid and polyethylene glycol.When esterification ratio of polyethylene glycol was 30%,there was a relatively low content of polyethylene glycol di-acrylate.When esterification ratio of the system increased to 85%, di-acrylate content increased to 18.2%,ratio of di-acrylate and mono-acrylate was 0.38, while the highest fluidity of cement paste added polycarylate superplasticizer was obtained as 275 mm.When the esterification ratio increased to 100%or higher, di-acrylate content increased much faster and mono-acrylate content decreased rapidly. Increasing of di-acrylate content in polyethylene glycol esterification product would cause not only crosslink of polycarboxylate superplasticizers but also gelation,which lead to poor performance of the superplasticizer. Based on work above,purified polyethylene glycol mono-acrylate was obtained and used for preparing of polycarboxylate superplasticizers.The fluidity of cement paste added the polycarboxylate superplasticizers reached above 300 mm,which was obviously better than the superplasticizer synthesized by unpurified polyethylene glycol acrylate.
polycarboxylate superplasticizers;;polyethylene glycol acrylate;;esterification reaction;;polyethylene glycol
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