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采用水溶液法,以次氯酸钠为氧化剂制取氧化淀粉,再经溶媒法以环氧乙烷作醚化剂将氧化淀粉醚化,制备出氧化-醚化淀粉型减水剂。通过红外光谱(IR)、凝胶渗透色谱仪(GPC)表征改性效果,以水泥净浆流动度为参考标准,考察羧基含量、醚化度对其减水能力的影响。结果表明:可溶性淀粉经氧化、醚化改性后分子量明显降低,当羧基含量为0.48%,醚化度(摩尔取代度)为0.5时减水剂减水能力最好。
An aqueous solution method was used to prepare oxidized starch with sodium hypochlorite as oxidant and etherified with ethylene oxide as etherification agent to prepare oxidized-etherified starch-type water reducer. The modification effect was characterized by infrared spectroscopy (IR) and gel permeation chromatography (GPC), and the fluidity of cement paste was taken as the reference standard to investigate the effects of carboxyl content and etherification degree on water reducing ability. The results showed that the molecular weight of soluble starch decreased obviously after oxidation and etherification. When the carboxyl content was 0.48% and the degree of etherification (molar substitution) was 0.5, the water reducing agent had the best water reducing ability.