High efficiency water reducer of poly-carboxylic acid as a new kind of building materials is in concentration of 20％-40％,which is unfavorable for storage and transportation,and limits its extensive application.The solid water reducer of poly-carboxylic acid was synthesized through bulk polymerization method without any solvent,in the presence of initiator (BPO),polymerized under the melting state.The optimum reaction conditions were as fellow:the molar ratio of crude materials was TPEG ∶ AA ∶ MAS =0.8 ∶ 3.25 ∶ 0.4,the dosage of initiator (BPO) was 1％ of the monomer weight,the temperature of reaction was 80℃,the time of initiator dropwising was 2 hours and the time of warm keeping was 1.5 hours.The crude product was poured out after cooling to room temperature,the end product was made after grinded as a powder.The powder of solid poly-carboxylic water reducing agent which was grinded to 0.125 mm can be dissolved in 46 seconds without any cementation in 150 days.The cement paste and concrete experiment results show that the product performance is better than that of the similar products at home.This preparation of high efficiency water reducer of solid poly carboxylic acid by bulk polymerization has advantages of simple process,easy operation,friendly environment,which opens up broad prospects for commercialization.%聚羧酸高效减水剂生产浓度一般为20％～40％(质量分数),不宜储存和运输,限制了其更广泛的应用.利用本体聚合方法合成固体聚羧酸减水剂,在不加任何溶剂的情况下,利用原料中大单体TPEG、丙烯酸的物理化学特性,通过合适的引发剂(BPO),实现反应原料熔融态下的聚合反应.最佳反应条件为TPEG∶AA∶ MAS=0.8∶3.25∶0.4(摩尔比),引发剂BPO用量为单体总质量的1％,反应温度为80℃,引发剂滴加时间为2h,保温时间为1.5h.反应结束后趁热将产物倒出,冷却至室温,经研磨成粉末,得到产品.实验得到的固体聚羧酸减水剂产品经研磨后无粘结现象,颗粒尺寸在0.125 mm时,46 s即可实现完全溶解,150 d未出现变质结块现象.通过净浆试验和混凝土试验对产品进行了性能测试,结果表明产品性能超过了国内同类固体聚羧酸高效减水剂的产品水平.本体聚合法制备固体聚羧酸高效减水剂工艺简单、操作容易、对环境友好,具有非常广阔的工业前景.
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