Copolymer emulsion lattices based on styrene (St) with methacrylate monomers, were synthesized with composition ratio (5/5) in the presence of a co-surfactants that consists of dodecyl benzene sodium sulfonate with polyvinyl alcohol (DBSS/PVA) and DBBS with polyoxyethylene glycol monomethyl ether (DBBS/ POE). The obtained latices were characterized by 1 H NMR, rheological and morphological techniques. The effect of latices on the physicomechanical properties of ordinary Portland cement (OPC) pastes was investigated. The results showed that the addition of water mixed to the cement with copolymer improves most of the specific characteristics of OPC.
T HREE different composition ratios of chitosan-g-acrylic acid, P[Ch-g-AA] were prepared in the presence of potassium persulphate as an initiator using free radical technique. The grafted copolymers were characterized through FT-IR, TGA, DSC, and SEM. The results showed that these grafted copolymers have a single glass transition indicating that these copolymers can form a miscible phase. The P[Ch-g-AA] exhibit thermal stability. SEM of the grafted copolymers showed no phase separation, when compared with the pure Ch. The effect of grafted copolymers on the physico-mechanical properties of cement pastes was investigated. The addition of water mixed with grafted copolymer to the cement, improves properties of cement pastes. As the ratios of AA in the grafted copolymer increases, the water-to-cement (WC) ratio, setting time as well as water absorption decreases. While The compressive strength was sharply increased at nearly all hydration ages.
In this study, three composition ratios of [polyvinyl alcohol (PVA)-2-ethylhexyl acrylate (2-EHA)] were prepared by grafting polymerization techniques in aqueous solution using ammonium persulfate as free radical initiator. The ratio of PVA/2-EHA in the grafted copolymers was variable: 1/ 8, 1/ 6 and 1/ 4, respectively. The obtained grafted copolymers were characterized by different techniques including FTIR, 1 H NMR, TGA and DSC. The copolymers were mixed with cement to study the physicomechanical properties of cement pastes including W/C ratios, setting time, workability, water absorption as well as compressive strength were investigated. The results showed that the addition of grafted copolymers to cement pastes affected the physicomechanical properties. As the content of 2-EHA in the grafted copolymers increased, the water of consistency decreased, whereas the setting times (initial & final) were shortened. The compressive strength of the cement pastes was increased at all ages of hydration while water absorption decreased with increasing 2-EHA.
The paper deals with the influence of blend polymers on the physico-mechanical properties of Portland cement pastes including, W/C ratio, setting time, workability, density, porosity and compressive strength. Blend polymers were used based on methyl cellulose (MC) of different molecular weight (4x10 4 and 8.3x10 4 g/mol) and poly(acrylic acid) (PAA). The result showed that, the physico-mechanical properties of the cement pastes are dependent on molecular weight of MC. However, the addition of MC/PAA blend into cement, the W/C-ratio, setting time and density decrease while the compressive strength and flow increase. Also blend polymer containing MC (8.3x10 4 g/ mol) is more effective than that containing MC (4x10 4 g/mol)
The physical and mechanical properties of mortar containing synthetic cosurfactants as air entraining agent are investigated. The cosurfactants consist of a combination of 2% dodecyl benzene sodium sulfonate (DBSS) and either 1.5% polyvinyl alcohol (PVA) or 1.5% polyoxyethylene glycol monomethyl ether (POE). Also these cosurfactants were used to prepare copolymers latex: styrene/butyl methacrylate (St/BuMA), styrene/methyl methacrylate (St/MMA), and styrene/glycidyl methacrylate (St/GMA), in order to study their effects on the properties of mortar. The properties of mortar examined included flow table, W/C ratio, setting time, water absorption, compressive strength, and combined water. The results indicate that the latex causes improvement in mortar properties compared with cosurfactants. Also polymer latex containing DBSS/POE is more effective than that containing DBSS/PVA.
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