Synthesis Of Polycarboxylic Acid High Performance Water Reducing Agent

In the concrete water-reducing agent industry,the polycarboxylic acid high performance superplasticizer is a new generation of green environmental water reducing agent.Compared with the previous series of water reducing agents,it has the advantages of low mixing amount,high water reducing rate,good slump retention,formaldehyde free and wide adaptability.Therefore,the research and development of this kind of water reducing agent has a wide application prospect.This project used polyethylene glycol(PEG),polyethylene glycol(MPEG)and hydrolyzed polymaleic anhydride(PMA)as raw materials,PMA as the main chain,PEG and MPEG as the side chain,and cyclohexane as solvent.The esterification reaction occured under the action of the catalyst.The high performance water reducing agent of macromolecular polycarboxylic acid with comb structure was synthesized and its properties were evaluated.This project adopted the orthogonal design test method.The effects of the molar ratio of esterification,the temperature of esterification,the amount of solvent and the amount of catalyst used on the final product were investigated in the experiment.The optimum reaction conditions are as follows: the molar ratio of hydrolyzed polymaleic anhydride to polyether is 0.55:1,the esterification temperature is 105?,the amount of solvent is 30% of the total reactant(dehydrating),and the amount of catalyst is 3%.A single factor comparison method was used to optimize the solvent amount of 25%,using sulfuric acid and p-toluene sulfonic acid as a mixed catalyst,and the amount was 3% of the total amount of reactant(water removal).At the same time,this paper also designed the refining method of the polycarboxylic acid high performance water reducing agent: using the principle of phase separation of polymer solution and removing all kinds of raw materials which are not reacted by the method of cooling,the purpose of purifying the product was achieved,the comprehensive performance of the water reducing agent was greatly raised,and the product of the project was further perfected.The test results showed that when the content of the polycarboxylate superplasticizer synthesized by the project was 0.2%(dewater),the fluidity of cement paste could reach 227 mm,and the fluidity of cement paste could reach 263 mm after refined products.In the concrete test of 0.25% of the concrete,the slump loss after 1 hours is 4.5cm,and its strength and soil resistance are better than those of the existing product PC-M1.In addition,the process flow design of 5000 tons polycarboxylate water reducing agent was designed.