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胶体粒子表面改性及其对水泥水化的影响
作者:蒋凌飞 卢子臣 孔祥明 蔡熠 
单位:清华大学土木工程系建筑材料所 北京 100084 
关键词:聚合物乳液 表面电荷 水泥水化 吸附 
分类号:TU53
出版年,卷(期):页码:2017,45(5):7-7
DOI:10.14062/j.issn.0454-5648.2017.05.00
摘要:

 通过乳液聚合制备了表面性质不同的两种阴离子乳液,即C4与CT乳液。C4乳液在制备过程中通过共聚甲基丙烯酸(MAA)使其中聚合物乳液粒子表面带负电荷,而CT乳液不仅共聚相同量的MAA单体,同时在合成中通过共聚异戊烯聚氧乙烯醚(TPEG),在乳液粒子表面引入非离子聚氧乙烯(PEO)毛梳层。通过水化热测试、颗粒表面电荷滴定、钙离子电极测试、等温吸附测试等实验探讨了两种乳液对水泥水化的影响及其内在机理。研究表明:与C4乳液相比,表面含非离子PEO毛梳层的CT乳液对水泥水化的抑制作用明显减弱。电荷密度滴定及钙离子电极测试表明聚合物乳液粒子表面毛梳层不会降低羧基官能团对钙离子的络合能力。吸附量测试结果表明非离子PEO毛梳层的引入显著降低了聚合物乳液粒子在水泥颗粒表面的吸附量,同时激光共聚焦显微镜直观观测证实了吸附量测试结果。因此两种乳液粒子在水泥颗粒表面吸附性能的差异是导致其对水泥水化不同影响的主要原因。

 

 Two types of anionic styrene-acrylate (SA) polymer latexes, C4 and CT, with different surface modifications were synthesized through emulsion polymerization. The negative charges of the colloidal particles of the two latexes originate from the copolymerized meth acrylic acid (MAA) in the polymer. Despite the same anionic charges, the surface of the colloidal particles in CT latex is coated by polyethylene oxide (PEO) hairy layer due to the incorporation of the polyethylene glycol macro-monomer (TPEG). The impact of the obtained latexes on the kinetics of cement hydration, and the corresponding mechanism were investigated by isothermal calorimetry, specific surface charge density measurement and calcium ion selective electrode, respectively. The results show that the surface modification of the colloidal particles by forming a PEO hairy layer can effectively minimize the retardation effect of polymer latexes on the cement hydration. In addition, the hairy surface in CT does not hinder the complexation of carboxyl group with Ca2+. The adsorption amount of two polymer latexes on cement grains indicates that the hairy surface of colloidal particles can reduce the adsorption amount of polymer on the surface of cement grains, which is well agreement with the result by confocal laser observation. Hence, different adsorption behaviors of CT and C4 latexes are due to their different impacts on the cement hydration.

 
基金项目:
国家自然科学基金联合基金(U1301241)资助。
作者简介:
参考文献:

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