Effects of nonionic surfactants on stability of latex in cement paste
To clarify why surfactants affect the stability of latex in cement pastes and why many latexes qualified in standard stability tests still coagulate when mixed with cement, several kinds of nonionic surfactants were selected to study the interactions among cement, latex and surfactant.
Results show that a higher affinity of surfactant to polymer contributes to a higher stability of latex in cement paste.
Phenyl better than alkyl
When surfactants have similar hydrophilic group with each other, surfactants with phenyl in hydrophobic group can more effectively improve stability of styrene-acrylate (SA) latex in cement paste than that with n-alkyl. With the same hydrophobic group (octyl phenyl) in molecules, surfactants with shorter hydrophilic group show better stabilisation effect on SA latex. The combined action of high Ca2+ concentration, high solid concentration, and mechanical shear during agitation process of cement paste is the decisive factor causing coagulation of latex.
The study is published in: Applied Polymer Science, Volume 135, Issue 10, March 10, 2018
