El-Sayed Negim

Effects of Surfactants on the Properties of Styrene/Methacrylate–Type Superplasticizer in Cement Paste

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 1H 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.

Effect of pH on the physico-mechanical properties and miscibility of methyl cellulose/poly(acrylic acid) blends

The miscibility behavior and physico-mechanical properties between methyl cellulose (MC) of different molecular weights (4 × 10(4) and 8.3 × 10(4)g/mol) and poly(acrylic acid) (PAA) were studied by viscometry, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), tensile strength and scanning electron microscopy (SEM) using water as a solvent. Various formulations were designed to investigate the effects of process variables such as pH on the physico-mechanical and miscibility properties of MC/PAA blends. The rheological features for the obtained blends are strongly dependent on the molecular weight of the MC used and pH. The viscosity measurements showed that all blends have non-Newtonian shear thinning (pseudoplastic) behavior. These blends have a single glass transition indicating that these blends are able to form a miscible phase due to the formation of hydrogen bonds between the hydroxyl group of MC and the carboxyl group of PAA. The MC/PAA blends exhibit good mechanical properties, thermal stability, characteristics of a MC-PAA polymer network. SEM of the blends showed no phase separation, when compared with the pure MC and PAA.

Effects of Surfactants on the Properties of Mortar Containing Styrene/Methacrylate Superplasticizer

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.

Preparation and Characterization of Acrylic Primer for Concrete Substrate Application

This study dealt with the properties of acrylic primer for concrete substrate using acrylic syrup, made from a methyl methacrylate monomer solution of terpolymers. Terpolymer systems consisting of methyl methacrylate (MMA), 2-ethylhexyl acrylate (2-EHA), and methacrylic acid (MAA) with different chemical composition ratios of MMA and 2-EHA were synthesized through bulk polymerization using azobisisobutyronitrile (AIBN) as initiator. The terpolymer composition is characterized by FTIR, 1H NMR, DSC, TGA, and SEM. The glass transition temperature and the thermal stability increased with increasing amounts of MMA in the terpolymer backbone. The effect of chemical composition of terpolymers on physicomechanical properties of primer films was investigated. However, increasing the amount of MMA in terpolymer backbone increased tensile and contact angle of primer films while elongation at break, water absorption, and bond strength are decreased. In particular, the primer syrup containing 65% 2-EHA has good bonding strength with concrete substrate around 1.1 MPa.

Effect of methyl methacrylate and butyl methacrylate copolymer on the physico-mechanical properties of acryl syrup for paints

The present study deals with the physico-mechanical properties of acryl syrups paint, which are made from copolymer powder and methyl methacrylate (MMA) monomer. Copolymer powders were used based on MMA and butyl methacrylate (BMA). The effect of copolymer powder to MMA- monomer ratio on the physico-mechanical properties acryl syrup mixes for paint applications was investigated. Testing included pot-life, curing time, viscosity, tensile strength, elongation, water absorption and hardness shore A. The results showed that, not only monomer composition of the copolymer but also the ratio of copolymer to MMA-monomer affected the physico-mechanical properties of acrylic films. The tensile strength, hardness, pot-life, curing time and hardness of the acrylic film increased with the increase of the MMA ratio in copolymer and decrease content of copolymer in acrylic syrup mixes. In conclusion, low copolymer content and high MMA ratio in copolymer (MMA/BMA) powders are desired to produce paint with physico-mechanical properties.

Effect of Copolymer Latexes on Physicomechanical Properties of Mortar Containing High Volume Fly Ash as a Replacement Material of Cement

This paper investigates the physicomechanical properties of mortar containing high volume of fly ash (FA) as partial replacement of cement in presence of copolymer latexes. Portland cement (PC) was partially replaced with 0, 10, 20, 30 50, and 60% FA. Copolymer latexes were used based on 2-hydroxyethyl acrylate (2-HEA) and 2-hydroxymethylacrylate (2-HEMA). Testing included workability, setting time, absorption, chemically combined water content, compressive strength, and scanning electron microscopy (SEM). The addition of FA to mortar as replacement of PC affected the physicomechanical properties of mortar. As the content of FA in the concrete increased, the setting times (initial and final) were elongated. The results obtained at 28 days of curing indicate that the maximum properties of mortar occur at around 30% FA. Beyond 30% FA the properties of mortar reduce and at 60% FA the properties of mortar are lower than those of the reference mortar without FA. However, the addition of polymer latexes into mortar containing FA improved most of the physicomechanical properties of mortar at all curing times. Compressive strength, combined water, and workability of mortar containing FA premixed with latexes are higher than those of mortar containing FA without latexes.