Research Of Synthetical Technics And Property About Polycarboxylic Acid Terpolymer Water-reducing Agent

The molecule of the polycarboxylic acid water-reducing agent is designed according to the "molecule design" theory and copolymerized through orthogonal experiments. First the big monomer containing polyoxyethylene group was synthesized with MA and PEG which is different at molecular weight. Then the polycarboxylic acid water-reducing agent, MPS is synthesized with the big monomer and MAS in the water. The technics of the esterification and the synthesization is optimized. The effect of the esterifying technics on the the ratio of esterifying and water-reducing property are discussed. And the effect of synthesizing technics on the water-reducing property is discussed too. The best condition of esterifying and polymerization is determined. The configuration of the water-reducing agent is confirmed by infrared spectrum. The water-reducing property and the quality index of the best water-reducing agent are mensurated according to the GB/T 8077-2000. The water-reducing property is discussed and the water-reducing mechanism is researched. Finaly, conclusion is gave:The structure of the polycarboxylic acid water-reducing agent synthesized in this paper is like comb. Its main chain is short and its branch chain is long. On its main chain there are some carboxyls and sulphonic groups which have different active property. On its branch chain there are some polyoxyethylene groups which have different length. So it has good water-reducing property and excellent dispersed impact. The maximal water-reducing ratio is 48%. The quality index accords with the standards of the country.Three series of the big monomer was synthesized. The condition of synthesization of MP-1 is that n_PEG:n_MA=1:1.1, 3h, 120℃, 6% of the dosage of the catalyzer, under which the esterifying ratio is the best, 73.28%. The condition of MP-2 is n_PEG:n_MA=1:2, 4h, 120℃, 6% of the dosage of the catalyzer, when the esterifying ratio is 54.71%. The condition of MP-3 is n_PEG:n_MA=1:1.1, 2h, 90℃, 4% of the dosage of the catalyzer, when the esterifying ratio is 32.41%.The research find that the water-reducing property is not the best with the increasing of the esterifying ratio. To MP-1, when the esterifying ratio is between 50.0%～57%, the water-reducing property is the best. To MP-2, when the esterifying ratio is between 31.5%～42.0%, the water-reducing property is the best. To MP-3, when the esterifying ratio is between 20.0%～26.5%,the water-reducing property is the best. Finally, the esters under the best water-reducing property are choosed to polymerize the water-reducing agent, which are 4# MP-1 with the esterifying ratio of 50.13%, 4# M1000 with the esterifying ratio of 40.57%, 7# MP-3 with the esterifying ratio of 26.6%The best technics of polymerization of MPS-Ⅰis n_MP-1:n_MAS=1:1,5h,95℃, 6% of the dosage of the catalyst, when the flow ability of cement paste is 283.5mm and the water-reducing ratio is 47.5%. The best technics of polymerization of MPS-Ⅱis n_MP-2:n_MAS=1:1,3h,85℃, 4% of the dosage of the catalyst, when the flow ability of cement paste is 274.5mm and the water-reducing ratio is 46.15%. The best technics of polymerization of MPS-Ⅲis n_MP-3:n_MAS=1:1, 5h, 95℃, 6% of the dosage of the catalyst, when the flow ability of cement paste is 293mm and the water-reducing ratio is 48.78%.The main mechanism of the polycarboxylic acid water-reducing agent, MPS, is space block function, interface energy reducing and lubricating effect. Meanwhile it has the function of importing air.