抗泥型聚羧酸减水剂的制备及性能

Preparation and properties of polycarboxylic superplasticizer with high tolerance to clay

以甲基丙烯酸(MAA)、甲基丙烯酸羟乙酯(HEMA)为单体,过氧化氢(H2O2)/抗坏血酸(Vc)为引发剂,甲基烯丙基磺酸钠(SMAS)为链转移剂,合成了一种抗泥型聚羧酸减水剂,通过红外光谱(FTIR)、凝胶渗透色谱(GPC)对聚合物进行结构表征,通过水泥净浆流动度、蒙脱土层间官能团、X射线衍射和吸附量测试,对其分散性能及抑制蒙脱土机理进行了探究。结果显示:合成的抗泥型聚羧酸减水剂在摩尔比为2.5∶1时分散性能最佳,当减水剂折固掺量为0.25%时,水泥初始净浆流动度为268mm;与普通聚羧酸减水剂相比,合成的抗泥型减水剂对蒙脱土敏感性较低,与蒙脱土作用后的层间未出现抗泥型减水剂的特征官能团,层间距为1.40nm,抗泥型减水剂在蒙脱土上的吸附量远小于普通减水剂的吸附量。

In this paper, a polycarboxylate superplasticizer with anti-clay was prepared using methyl acrylic acid（MAA） and hydroxyethyl methacrylate（HEMA） as monomers, hydrogen peroxide（H2O2）and ascorbic acid（Vc） as initiators, and methyl propene sulfonate（SMAS）as the chain transfer agent. The copolymer was characterized by a Fourier transform infrared spectrometer（FTIR）and gel permeation chromatography（GPC）. The dispersion properties and mechanism of tolerance to montmorillonite were explored by tests of fluidity, functional group of montmorillonite interlayer, X ray diffraction, and adsorption amount. The results show that the superplasticizer with anti-clay has better dispersing performance at n（MAA）∶n（HEMA）=2.5∶1;the initial fluidity of cement paste can exceed 268 mm when the dosage of superplasticizer is 0.25% of cement mass. The superplasticizer with anti-clay shows low sensitivity to montmorillonite compared to common superplasticizers. The interlayer spacing of montmorillonite modified with newly-synthesized superplasticizers is 1.40nm; the adsorption amount on montmorillonite particles is far less than those of conventional superplasticizers.