| Development of poly-acrylic series water-reducing agent(WRA) was a modern frontier research project. The poly-acrylic WRA was characteristic of lower additive, higher fluidiffication effect, and preventing concrete mix from slump-loss with time duration. The domestic research of poly-acrylic WRA was at first step now.In this paper, a new class of concrete high performance water reducer (HPWR) was designed from chemical classification of high performance WRA, working principle and unit structure model of poly-carboxylate series WRA. The comb-like copolymer structure of HPWR was "carboxylic group-ether link-ester link". The synthetic chemical materials was polyethylene glycil, acrylic acid and methyl-metacrylic acid ester.Using the method of "Purpose Building", a series new monomer-polyoxyalkyene macromer(PEA) were synthesized by poly-oxyethlene side chains with synthesis technology in macromer. PEG and superfluous AA reaction by complete concatenation method, the esterify production "esterify water" and acid number were mensurated, it shows that the esterify reaction would be processed under 100℃ esterify temperature and with amine accelerantThe tide of esterify reaction was substantiated by IR. In the IR spectrum, the characteristic peak of hydroxy of PEG and carboxyl of AA were weakened.and the ester link of PEG was reinforce. The "esterify water" was increased gradually and the acid number of esterify production was debased gradually along with the extent of esterify time and the augmentation of molecular weight of PEG. When the reaction time was SOOmin, the acid number of esterify production was least. It shows that hydroxy peak of PEA4 would be least at 300min, the hydroxy peak of PEA23 was almost disappeared at 120min. In macroscopical side, the acid number can only indicate that superflous AA was reduced along with esterify reaction and pumping water. In microcosmic side, the different molecular weight of PEA esterify time was reduced along with the augmentation of molecular weight were approved.The mixture of PEA series esterify production ,AA, MMA were processed tercopolymer by concatenation drop adding fashion during the nitrogen gas protect. Thepreparation of chain transfer, the mol percent of PEA:AA:MMA and the time of combind were systermic investigated.The performance of PC was refledted by the neat cement paste fluidity and fluidity losing .The results indicated: (1) The preparation of chain transfer was one of most factor of control the molecular weight of copolymer and influence the performance of PC. When the dosage was 8%AA,the effect was best. (2) The performance of PC was decided with the proportion of PEA,AA,MMA. The fluidity of copolymer would augment if the dosage of AA increase, but when dosage of AA was 75%, it was hard to control the compose reaction, and dispersion of PC would depress; When PEA degree of polymerization augment the air-entraining of MMA would increase; it would produce floe and hard to control the compose reaction when the dosage of PEA4 more than 15%,PEA23 more than 25%. (3) The degree of polymerization of PC was most factor of the influence of neat cement paste fluidity and fluidity losing .PEA4 copolymer have biggish fluidity losing because lengh of side-chain was short and static electric repulsion was finity. In other way, PEA23 copolymer have small fluidity losing because lengh of side-chain was long and static electric repulsion was strengthen .If side-chain was too long ,the static electric repulsion was strong, but the effect of dispersion of PC would reduce. (4) The neat cement paste fluidity of copolymer would augment and the cohesiveness of cement would increase along with augmentation of PEA dosage, but if the dosage was too big , the dosage of AA would be reduced, so it would reduce the carboxylic content of copolymer, and performance of water reduce would weaken , the dosage of PEA23 can not more than 25%.(5) The effect of water reduce would increase if the copolymer time increase. The fluidity of copolymer have no more augmentation after... |
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