Synthesis And Application Of Monomethyl Maleate Polycarboxylate Superplasticizer

With the development of high performance concrete and commercial concrete, The requirement for concrete admixture becomes higher and higher. The polycarboxylic acid superplasticizer has been paid more and more attention by concrete engineering world, because of its higher water-reducing ratio, lower slump loss and excellent enhancement effect. Research and development of new product with more excellent performance and applicability has important theoretical and practical value, which is also the main development direction of concrete additive.According to the mechanism of polycarboxylic superplasticizer, the maleic anhydride polymer is selected as macromolecular main chain on which there are side chain structure of a carboxyl, ester, and poly vinyl. In this paper, by analysing its preparation process and the performance, the results showed that the synthetic polycarboxylate superplasticizer possess characteristic of higher water-reducing ratio, adaptability to different cement and excellent preparation performance.First of all, the small monomer of the maleic acid monomethyl ester has been synthesized by the reaction of unlocking ring over maleic anhydride which was in excess of methanol. The reaction was in the nature of no solvent, no catalyst, no separation of the final product at room temperature, etc. Besides, this study was suitable for industrial production. By examining the anhydride alcohol feed ratio, reaction time and reaction temperature on the impact of technology, we has found optimum conditions of the reaction and analyzed maleic acid monomethyl ester by Infrared (IR) and NMR characterization.By means of using ammonium persulfate initiator and solution polymerization, the polycarboxylic acid superplasticizer was prepared by the reaction of maleic acid mono methyl ester, maleic anhydride and allyl vinyl ether copolymer polyoxyethylene. In this study, we have found the optimum conditions of polymerization by exploring the monomer molar ratio, the amount of initiator, reaction time, reaction temperature, the properties of synthesizing monomer polycarboxylate superplasticizer which was effected the large molecular weight. Furthermore, the synthesized polycarboxylate superplasticizer was characterized by gel chromatography and infrared spectra.The performance of superplasticizer need to be tested concretely, through a series of concrete cement tests, it is found that polycarboxylate superplasticizer is in capacity of high water-reducing ratio and excellent slump retention.Finally, the properties of adsorption between polycarboxylic acid superplasticizer and cement has been studied by gel chromatography which detected the adsorption both cement particles and superplasticizer. Besides, the relation of adsorption and dispersion has been shown by testing the adsorptive capability of standard cement and common cement in the market.