中国胶粘剂

以烯丙基聚乙二醇(APEG)和丙烯酸(AA)为单体,以过氧化氢(H₂O₂)/抗坏血酸(Vc)为二元引发体系,制备聚羧酸减水剂(APEGAA)。通过改变单体的物质的量比、H₂O₂和Vc质量比、H₂O₂用量、链转移剂(TPA)用量、反应温度和反应时间,来研究其对减水剂性能的影响。研究结果表明:H₂O₂/Vc二元引发体系制备减水剂的较佳工艺为,n (AA):n (APEG)=4.2:1,w(H₂O₂)=0.52%,m (H₂O₂):m (Vc)=3:1,w(TPA)=0.34%(均相对于单体总质量而言),反应温度60℃,反应时间6 h。该工艺制备的减水剂具有较好的分散性,当减水剂折固掺量为0.2%时,水泥净浆初始流动度为270 mm。混凝土试验表明,APEGAA减水剂的减水率高于两种对比的早强型聚羧酸减水剂,其保坍性能和早强效果优于两种对比的早强型聚羧酸减水剂。

The polycarboxylate superplasticizer(APEGAA) was prepared by using allyl polyethylene glycol(APEG) and acrylic acid(AA) as monomers,and hydrogen peroxide(H₂ O₂)/ascorbic acid(Vc) as binary initiator system.The effects of the molar ratio of monomer,the mass ratio of H₂ O₂ and Vc,the amount of H₂ O₂,the amount of chain transfer agent(TPA),reaction temperature and reaction time on the performance of superplasticizer were studied.The research results showed that the optimum process for preparing superplasticizer by the H₂ O₂/Vc binary initiator system was n(AA):n(APEG)=4.2:1,w(H₂ O₂)=0.52%,m(H₂ O₂):m(Vc)=3:1,w(TPA)=0.34%(all relative to the total mass of monomers),reaction temperature was 60℃,and reaction time was 6 h.The superplasticizer prepared by this process had good dispersion performance,and the initial fluidity of cement paste was 270 mm when the converted solid content of superplasticizer was 0.2%.The concrete test showed that the water reducing rate of APEGAA superplasticizer was higher than those of two kinds of early-strength polycarboxylate superplasticizer,and the slump retention performance and early strength effect were better than those of two kinds of early-strength polycarboxylate superplasticizer.