Study On Synthesis And Properties Of Polycarboxylate Superplasticizer

High temperature synthesis of polycarboxylic acid superplasticizer has been relatively mature,but the process is complex,high energy consumption,high temperature synthesis by energy and environmental protection restrictions.Low temperature technology is still very immature,systematic study of low temperature synthesis of polycarboxylic acid superplasticizer using ammonium persulfate/sodium chloride as REDOX system has not been reported.Starting from low-temperature synthesis,this project selects ammonium persulfate/sodium bicarbonate REDOX system,designs and produces low-temperature polycarboxylic acid water reducer with simple process,low energy consumption,low content and high water reduction rate,and realizes industrial transformation.In order to further reduce APS activation energy and thus reduce reaction temperature,this study introduced sodium formaldehyde sulfoxylate as a reducing agent to form a REDOX system with APS.Polyether monomer HPEG and acrylic acid were used as the main reaction materials,and 3-mercapto propionic acid was used as chain transfer agent to polymerize at low temperature.Finally,low temperature polycarboxylic plasticizer was obtained.The effects of acid-ether ratio,ammonium persulfate dosage,3-mercaptopropionic acid dosage and reaction temperature were discussed.Finally,the better ratio and technological conditions were determined.The results show that the optimal ratio of test(mole ratio)is acid ether than 4.5:1,mercapto propionic acid and ether ratio is 0.095:1,ammonium persulfate and ether ratio is 0.074:1,ammonium persulfate and sodium formaldehyde sulfoxylate ratio of 3:1,synthetic is the best temperature range of 25 to 40?.The infrared spectrogram of the low-temperature polycarboxylic superplasticizer was analyzed,and its main functional groups included carboxylic group,hydroxyl group and polyether-polyethylene glycol group,which were consistent with the designed structure.After a series of process and equipment parameters adjustment,the industrial production of the product is realized.In industrial production,the temperature of the reaction system rises due to the concentrated heat release of the reaction,so the temperature needs to be controlled by cooling water.During the production,through optimizing the heat preservation time and polyether feeding process,the process was simplified smoothly,manpower was saved,and the product quality was guaranteed.The effects of low-temperature polycarboxylic superplasticizer reducer and high-temperature product on hydration heat,adsorption and concrete properties were compared and analyzed.At present,the low-temperature synthetic polycarboxylic superplasticizer product developed in this project has been widely promoted in practical concrete engineering,with good application performance and unanimous praise in concrete engineering.