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保坍型聚羧酸减水剂的研究 总被引:1,自引:0,他引:1
以聚醚,丙烯酸为主要原料,在水体系中通过氧化还原引发,合成聚羧酸减水剂。试验表明,该减水剂具有较高的减水率和优异的保坍性。 相似文献
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以丙烯酸和甲氧基聚乙二醇为主要原料,采用直接酯化法合成了聚羧酸系减水剂大分子单体(甲氧基聚乙二醇丙烯酸酯)。探讨了丙烯酸与甲氧基聚乙二醇摩尔比、催化剂和阻聚剂的用量、反应温度及反应时间对酯化反应的影响。得出最佳合成条件:丙烯酸与甲氧基聚乙二醇摩尔比为1.5,对甲苯磺酸的用量为甲氧基聚乙二醇质量分数为3%,对苯二酚的用量为丙烯酸质量分数的1.5%,甲苯用量为反应物总量的30%,反应温度为130℃,反应时间为6 h,酯化率可达96.8%。 相似文献
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Effects of polyethlene oxide chains on the performance of polycarboxylate-type water-reducers 总被引:4,自引:0,他引:4
A series of polycarboxylic acid-based copolymers with block and graft groups of polyethlene oxide (PEO) chains was synthesized; effects of the different PEO chains on the fluidity, Zeta potential and adsorption in cement paste and performances of the copolymer in concrete were discussed. It was proved that properties of the copolymer were affected by the length and density of PEO graft and block chains, and that copolymers with some block PEO chains at a certain length and moral percent had good performances in the water-reducing capability and fluid-retaining ability. Experimental results indicated that this kind of copolymers could be used as a high-range water-reducer because of the effects of electrostatic repulsive force and steric hindrance; one of its applications was to produce high-flowing concrete by incorporating with mineral admixtures, such as fly ash, etc. 相似文献
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梳形聚羧酸系减水剂的制备、表征及其作用机理 总被引:42,自引:0,他引:42
聚羧酸系减水剂具有高减水率和控制混凝土坍落度损失等优点,研究开发新型聚羧酸系减水剂受到广泛关注。以甲基丙烯磺酸钠、2-丙烯酰胺-2甲基丙磺酸、丙烯酸、不同聚氧化乙烯基(polyoxyethlene group,PEO)链长的聚乙二醇丙烯酸酯等单体制备了改进聚羧酸系减水剂(modified polycarboxylic water-reducers,MPC)。表征了MPC的分子结构与性能,讨论了MPC的分散稳定机理。研究表明:MPC具有梳形分子结构,应用MPC后混凝土的减水率能达到25%以上,其分散性与分散保持性能与减水剂的PEO侧链长短有关,其主要通过立体位阻起作用。 相似文献
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以丙烯酸和甲氧基聚乙二醇为主要原料,采用直接酯化法合成了聚羧酸系减水剂大分子单体(甲氧基聚乙二醇丙烯酸酯)。探讨了丙烯酸与甲氧基聚乙二醇摩尔比、催化剂和阻聚剂的用量、反应温度及反应时间对酯化反应的影响。得出最佳合成条件:丙烯酸与甲氧基聚乙二醇摩尔比为1.5,对甲苯磺酸的用量为甲氧基聚乙二醇质量分数为3%,对苯二酚的用量为丙烯酸质量分数的1.5%,甲苯用量为反应物总量的30%。反应温度为130℃,反应时间为6h,酯化率可达96.8%。 相似文献
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