水溶性单体对聚合物乳液在水泥浆体中稳定性的影响

以水泥浆的流动性和筛上残余率为评价指标研究了水溶性单体丙烯酸(AA)、N-羟甲基丙烯酰胺(NMA)、甲基丙烯酸羟乙酯(HEMA)单独使用或组合使用对聚合物乳液在水泥浆中稳定性的影响,并对其影响机制进行探讨。结果表明,不管水溶性单体是单独使用还是组合使用,随其总含量(0%~4%)的增加,聚合物乳液在水泥浆中的稳定性增加。在相同含量时,不同结构的水溶性单体对聚合物乳液在水泥浆中稳定性的贡献大小为NMAAAHEMA,与它们的无机性值/有机性值的比值有着很好的一致性。水溶性单体的含量和种类决定着聚合物乳液的钙离子临界凝聚浓度(CCC),聚合物乳液的CCC值越高,其在水泥浆中稳定性越好。水溶性单体越倾向于分布在乳胶粒表面,越有利于聚合物乳液的稳定。

Making Latex Suitable for the Modification of Cement Paste by Selecting Water-soluble Monomer

Three water-soluble monomers with different molecular structures were selected to prepare the styrene-acrylate latex used for the modification of cement-based materials .The flowability test and the residue on sieve test of cement paste were applied to evaluate the stability of latex in cement paste .Results show that the stability of latex in cement paste increases with the increase of water-soluble monomer content (0％ —4％ ) .At the same content of water-soluble monomer ,the latex containing N-methylol acrylamide (NMA) has the best stability when mixed with cement ,followed by the latex containing acrylic acid (AA) ,then the latex containing hydroxyethyl methacrylate (HEMA) .Which shows a good accordance with the inorganic value/organic value (I/O) of water-soluble monomer (I/O:NMA>AA> HEMA) .It is also found that the content and structure of water-soluble monomer determine the critical coagulation concentration (CCC) of latex ,and the higher CCC leads to the better stability of latex in cement paste .The greater the tendency of water-soluble monomer distributed on the surface of polymer particles contributes to the better stability of latex .