硅酸盐学报

以N-氨基甲酰马来酰亚胺(NCM)和氯代聚乙二醇单甲醚(CMPEG)为单体,在氢氧化钠作用下,合成N-聚乙二醇单甲醚-N’-氨基甲酰马来酰亚胺(MPNCM)减水剂大单体,并对MPNCM的结构进行表征。以净浆流动度和反应转化率为指标,考察了NCM/CMPEG摩尔比、引发剂用量、反应温度和反应时间等因素对净浆流动度和反应转化率的影响。结果表明:NCM/CMPEG摩尔比为1.2、引发剂用量(质量分数,下同)为0.8%、45℃反应4 h所制的大单体的分散性能较为适宜。以最佳反应条件制得的MPNCM与丙烯酸(AA)为原料,共聚合成聚羧酸系减水剂,并对聚羧酸系减水剂的减水性能和分散性能进行检测。结果表明:当聚羧酸系减水剂掺量为0.2%时,减水率达25.7%,混凝土净浆流动度为315 mm。

N-methoxypolyethylene glycols-N'-carbamoyl maleimide(MPNCM) was prepared with chlorophthalic methoxypolyethylene glycols(CMPEG), N-carbamoyl maleimide(NCM) and sodium hydroxide as a catalyst. The molecular structure of MPNCM was characterized. Effects of n(NCM)/n(CMPEG)(in mole ratio), degree of initiator, reaction temperature and reaction time on the conversion ratio and initial fluidity as a measurement index were investigated. The result shows that the optimal MPNCM can be obtained at the n(NCM)/n(CMPEG) ratio of 1.2, the amount of initiators of 0.8%(mass fraction, the same below) based on the mass of CMPEG and NCM, the reaction temperature of 45 ℃ and the reaction time of 4 h. The polycarboxylate based superplasticizer(SP) was synthesized with acrylic acid(AA) and the MPNCM prepared under the optimal condition, and the dispersion and water-reducing performance of SP were analyzed. It is indicated that the water-reducing ratio is 25.7% and the initial fluidity of cement paste is 315 mm when the dosage of SP is 0.2%.