Synthesis and Characterization of Styrene Copolymer Latices
and Itís Application in Cement
S.M. Negim1, M.M. H. Ayoub1, G.M. Enany2 and G.A. Mun3
1Department of Polymers and Pigments,
2Department of Physical and mathematical, Faculty of
3Department of Macromolecular Chemistry,
Copolymer emulsion latices based on styrene (St) with butyl acrylate (BuA) were prepared in presence of potassium persulfate/sodium metabisulfite (KPS/NaMBS) as redox initiation system and a coemulsifier that consists of dodecyl benzene sodium sulfonate with polyvinyl alcohol (DBSS/PVA) as well as DBSS with polyoxyethylene glycol monomethyl ether (DBSS/POE). 1H NMR, rheological and morphological techniques were investigated to characterize the obtained latices. The viscosity measurements showed that all lattices behave as a non-Newtonian shear thinning (pseudoplastics). The morphological characteristics of the obtained latices revealed that the latex particles prepared in presence of (DBSS/POE) as coemulsifier have the highest average volume particle diameter (Dv) compared with those obtained for the latices prepared in presence of (DBSS/PVA). The effect of styrene copolymer latices on the physicomechanical properties of ordinary Portland cement (OPC) pastes was investigated. As the concentration of the copolymer increases, both water-to-cement ratio (W/C) and setting time decrease. This means that these polymers act as superplastisizers. The combined water content and compressive strength of the OPC pastes premixed with these polymers were increased while the total porosity decreased at all curing ages up to 90 days.