酯类降黏型聚羧酸减水剂的合成与性能研究

Synthesis and performance of ester type viscosity-reducing polycarboxylate superplasticizer

采用自制的聚乙二醇单甲醚马来酸酐酯(MPEGMAH)降黏大单体与甲基丙烯酸(MAA)、甲基丙烯磺酸钠(SMAS)等小单体,以过硫酸铵[(NH_(4))_(2)S_(2)O_(8)]为引发剂、巯基丙酸(MPA)为链转移剂,通过自由基溶液共聚制得降黏型聚羧酸减水剂。研究了酸醚比[n(MAA):n(MPEGMAH)],SMAS、MPA、(NH_(4))_(2)S_(2)O_(8)用量以及反应温度对合成减水剂性能的影响。结果表明,当聚合反应温度为105℃、酸醚比为4.2,SMAS、MPA、(NH_(4))_(2)S_(2)O_(8)用量分别为MPEGMAH质量的0.7%、0.3%、5%时,制备的降黏型聚羧酸减水剂保坍性能好、混凝土排空时间短,综合性能最佳。

The viscosity-reducing polycarboxylate superplasticizer was obtained by free radical solution copolymerization,using the self-made polyethylene glycol monomethyl ether maleic anhydride ester(MPEGMAH),methacrylic acid(MAA)and sodium methallyl sulfonate(SMAS)as monomers,ammonium persulfate as initiator and mercaptopropionic acid(MPA)as chain transfer a gent.The effects of acid to ether ratio[n(MAA):n(MPEGMAH)],SMAS,MPA,(NH4)_(2)S_(2)O_(8) dosage and reaction temperature on its properties were studied.The results showed that when the polymerization reaction temperature was 105℃,the ratio of acid to ether was 4.2,the dosage of SMAS,MPA,and(NH4)_(2)S_(2)O_(8) was 0.7%,0.3%and 5%of MPEGMAH mass,the prepared viscosity-reducing polycarboxylate superplasticizer was of good slump retention property,short concrete empty time and the best comprehensive perfor-mance.