Effect of silane modified styrene-acrylic emulsion on the waterproof properties of flue gas desulfurization gypsum

Abstract Silane-modified styrene-acrylic emulsion was prepared with isobutyl acrylate, styrene, methyl methacrylate, vinyltriethoxysilane and long-chain trimethoxysilane. It was used as a waterproofing agent, its effect on the waterproof properties of flue gas desulfurization (FGD) gypsum was studied and the underlying mechanism was analyzed. The results show that when the silane-modified styrene-acrylic emulsion was added at 0.1% by mass, the FGD gypsum had a softening coefficient of 0.72, compressive strength of 9.0 MPa and water absorption rate of 36%. Compared with those of blank sample, the softening coefficient and compressive strength of this FGD gypsum increased by 148% and 18%, respectively, and the water absorption rate decreased by 33%. The waterproofing mechanism of silane-modified styrene-acrylic emulsion was studied by IR, XRD and SEM. It was found that the silane-modified styrene-acrylic emulsion formed a strong hydrophobic film on the surface of the FGD gypsum crystals. This film could inhibit the growth of FGD gypsum crystals, increase the effective overlap between crystals, and increase the water resistance of FGD gypsum.