硅烷改性聚羧酸减水剂-Na2SO4-水泥体系分散及流变性能的研究

采用γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570),丙烯酸(AA)以及甲基烯丙基聚氧乙烯醚(HPEG)单体,通过自由基聚合法合成了硅烷改性聚羧酸减水剂(SPC).试验研究了引入硅烷官能团后,减水剂分子成分、电荷密度以及对Na2SO4-水泥体系分散及流变性能的影响规律.研究结果表明,在SPC红外特征峰中发现了Si-O的伸缩振动峰,说明SPC成功引入硅烷官能团;电荷密度测试表明,PC比SPC具有较高的-COO-含量;通过分散性能、流变性能及吸附量测试,表明与PC相比,SPC能够通过≡Si-OH与水泥颗粒表面的-OH发生化学缩合反应,提高减水剂分子在Na2SO4-水泥体系中对水泥颗粒表面的吸附能力,降低屈服应力和塑性粘度,从而提高减水剂对水泥浆体的分散及流变性能.

Dispersion and Rheological Properties of Silane Modified Polycarboxylate Superplasticizer-Na2SO4-Cement System

A series of silane modified polycarboxylate superplasticizer (SPC) were synthesized via the radical polymerization in aqueous solution, in which γ-methacryloxypropyltrimethoxysilane (KH570), acrylic acid (AA) and methyl allyl polyoxyethylene ether (HPEG) were used.The effects of molecular composition and charge density of PC and SPC were studied.And dispersion and rheological properties of Na2SO4-cement system were also studied after the introduction of silane functional groups.The results show that the stretching vibration peak of Si-O is found in the SPC infrared characteristic peak, which indicates that the silane functional group is successfully introduced by SPC.The charge density test indicated that PC had higher-COO-content than SPC.Compared with the PC, the ≡Si-OH of SPC can react with-OH on the surface of cement particles, so SPC can improve the adsorption capacity of superplasticizer molecules on the surface of cement particles in Na2SO4 cement system, and reduce the yield stress and plastic viscosity.Thereby improving the dispersion and rheological properties of the superplasticizer molecules to the cement paste.