聚羧酸在水泥表面覆盖面积对分散性能的影响

Impact of surface coverage area of polycarboxylate superplasticizers on the dispersion of cement paste

通过自由基热聚合和可逆加成-断裂链转移法合成了不同主链刚柔性、不同序列结构分布的聚羧酸(polycarboxylate superplasticizer,PC)模型分子,系统的考察了PC分子结构与溶液构象、吸附性能以及宏观性能(如分散性能、流变性能)的关系,发现不同结构的PC宏观分散性能的差异主要来自于PC在水泥颗粒表面覆盖面积的差别。而PC的表面覆盖面积由两方面决定,一方面PC在水泥颗粒表面的单分子吸附层厚度;另一方面是PC在水泥颗粒表面的吸附量。单分子吸附层厚度越厚,在水泥颗粒表面的吸附量越大,PC在水泥颗粒表面的覆盖面积越大,对水泥浆体的分散性能越好。

Polycarboxylate superplasticizer（PC）with different backbone flexibilities and sequence structures has been synthesized by free radical polymerization and reversible addition-fragmentation chain transfer polymerization.The influence of molecular structure on the solution conformation,adsorption property and macroscopic property such as dispersion ability as well as rheological property has been investigated systematically.It is indeed noted that the difference of surface coverage area onto cement particle surfaces result in the difference of the dispersion of cement paste.Furthermore,the difference of surface coverage area mainly comes from the single molecular adsorbed layer thickness and the adsorption amount.The thicker adsorbed layer thickness along with the larger adsorption amount leads to the greater surface coverage area,and inevitably the better dispersion ability.