Synthesis Of Modified Sodium Carboxymethylcellulose Polymers And Its Application In Cement-based Materials

The graft copolymer was synthesized in aqueous medium,using sodium carboxymethyl cellulose(CMC)as the substrate,potassium persulfate as the initiator,sodium p-styrenesulfonate(SSNa)as monomer 1,vinyl acetate(VAc)and methyl allyl polyoxyethylene ether(HPEG)as monomer 2.Choosing the initiator dosage,the dosage of two monomers,temperature,the dosage ratio of two monomers and so on as variables,designed orthogonal experiment.Synthesizing latex according to orthogonal experiment,the latex was added to cement mortar,then determined the optimum reaction conditions according to the mechanical properties of cement mortar.Purifying the polymer,the polymers was characterized using Fourier transform infrared spectroscopy,X-ray diffraction,scanning electron microscope and thermogravimetric analysis.The polymer emulsion which was synthesized under the optimum reaction conditions was added to cement mortar.The effect of polymer on hydration of cement was analyzed by Fourier transform infrared spectroscopy,thermogravimetric analysis and differential scanning calorimeter.The experimental results showed that when the curing periods of samples were 28 days,polymer promoted the hydration of cement.The polymer emulsion which was synthesized under the optimum reaction conditions was added to cement mortar.The effects of water cement ratio and polymer cement ratio on the mechanical properties of cement mortar were investigated.The experimental results showed that when polymer-to-cement weight ratio and water cement ratio was 1.0%and 36.2%respectively,the mechanical properties of samples modified with polymer CMC-PSSNa/PVAc were the best.When polymer-to-cement weight ratio and water cement ratio was 1.0%and 40.0%respectively,using the polymer CMC-PSSNa/PHPEG as additive,the curing of modified samples after 3 d,7 d and 28 d,the flexural strength was increased of 31.46%,21.79%and 10.59%respectively.Moreover,the sodium lignosulfonate which was used as dispersants,the tributyl phosphate which was used as defoamers,was added to cement mortar.The effects of additions of tributyl phosphate and sodium lignosulfonate on the mechanical properties of cement mortar were investigated.The experimental results showed that when the dosage of sodium lignosulfonate and tributyl phosphate is 0.6%and 0.3%respectively,the mechanical properties of samples modified with polymer CMC-PSSNa/PVAc were the best.The polymer emulsion which was synthesized under the optimum reaction conditions was added to cement concrete.The experimental results showed that the water-reducing rate of polymer CMC-PSSNa/PVAc was higher than 15.0%.The water-reducing rate of polymer CMC-PSSNa/PHPEG was close to 20.0%.When polymer-to-cement weight ratio and water cement ratio was 1.0%and 47.17%respectively,using the polymer CMC-PSSNa/PVAc as additive,the curing of modified samples after 3 d,7 d and 28 d,the compressive strength was increased of 74.92%,57.01%and 25.66%respectively.When polymer-to-cement weight ratio and water cement ratio was 1.0%and 44.40%respectively,using the polymer CMC-PSSNa/PHPEG as additive,the curing of modified samples after 3 d,7 d and 28 d,the compressive strength was increased of 101.23%,70.23%and 36.84%respectively.