聚羧酸系高效减水剂的合成研究

Study on Synthesis of Polycarboxylic High Performance Water Reducing Agent

以过硫酸铵为引发剂,在75℃下,pH为中性时,用马来酸酐(MA)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、α-甲基丙烯酸(α-AA)和丙烯酸丁酯(BA)单体在水溶液下接枝共聚合成聚羧酸系高效减水剂。其性能与合成时采用的单体比例、温度、pH值、引发剂添加量和引发剂添加方法、水灰比等有关。通过实验发现,其中单体最佳比例为m(MA)/m(AMPS)/m(α-AA)/m(BA)=1︰8︰12︰1,pH值为中性,引发剂添加量为单体质量的10%,反应温度为75℃时得到的聚合物的性能最佳。通过性能检测发现,该减水剂具有优良的分散能力与流动保持性,它的减水率最高达到了28%(减水剂掺量为水泥质量的1%),水泥静浆流动度(扩展度)达到了197 mm以上,而且在60 min内几乎无坍落度损失,水泥浆体粘聚性好。

Using ammonium persulfate as indicator ,in the case of 75 ℃ and pH about 7, the polycarboxylic high performance water reducing agent, grafted copolymer of maleic anhydride, 2-acrylamido-2-methylpropanesulfonic acid （AMPS）,and methylacrylic acid （a-AA） , was synthesized in the aqueous system. The performance of this product is decided by monomers ratio, temperature, pH value, dosage adding method of initiator during synthesis. The test shows that the best synthesis conditions are as follows： ratio of MA/AMPS/α-AA/BA is 1 ： 8 ： 12 ： 1, reaction temperature is 75 ℃, pH value is about 7, initiator dosage is 10% of total amount of monomers. Through performance examination, this product has a good dispersing ability and long keeping time of fluidity, its water reducing ratio can reach 28% （dosage of water reducing agent is 1% of cement weight）, cement paste fluidity can reach above 197mm without slump in 60 min , cement paste has good viscosity polymerization.