【作者】 余铖；

【导师】 张智强；

【作者基本信息】 重庆大学 ， 材料科学与工程， 2008， 硕士

【摘要】 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,是高效减水剂的发展方向。本论文详细介绍了国内外高效减水剂的研究应用现状,分析了聚羧酸系减水剂的合成方法及发展趋势,并且从化学结构、作用机理入手,通过分子设计,合成出了含羟基、羧基、磺酸基、聚氧乙烯基等基团的具有梳型分子结构的聚羧酸系高效减水剂。课题选用烯丙醇聚氧乙烯醚(APEG)、丙烯酸(AA)、马来酸酐(MAD)与甲基丙烯磺酸钠(SMAS)为原材料,在引发剂过硫酸铵(APS)引发下进行自由基聚合,得到聚羧酸减水剂。试验结果表明:当单体APEG:AA:MAD:SMAS摩尔比为3:4:8:3时,该共聚物有较好分散性能。同时确定了最佳反应条件:引发剂用量为反应物总质量的2%;合成浓度为25%;温度为85℃;反应时间为4h。通过对自制PC红外光谱分析表明,分子中含有羧基、磺酸基和醚基等多种官能团。并对其进行了一系列水泥、混凝土试验,结果表明:自制PC对水泥浆体有较好的分散性能,与水泥的相容性好配制的混凝土有较好的保坍性,当掺量为0.3%时,减水率可以达到32.4%,各龄期抗压强度比均超过160%,性能远优于萘系减水剂,可应用于混凝土行业。通过对自制PC溶液的表面张力、水泥颗粒表面ζ电位和吸附量的测定,进一步分析了聚羧酸减水剂的作用机理。其减水作用机理主要为减水剂与水泥粒子之间的吸附-分散作用,即在减水剂-水-水泥体系中减水剂吸附在水泥颗粒表面,形成双电层,从而产生静电斥力作用,而在吸附过程中,其主链上的长侧链可在体系中充分伸展而发挥空间立体位阻作用,因此具有更好的分散性和分散保持性。通过综合性能评价,自制PC具有一定的性能和价格优势,应用前景良好。更多还原

【Abstract】 Polycarboxylic acid type water-reducer which exhibit an excellent ability of water-reducing and prevention of slump loss,represent the trend of warer-reducers for concret in the future.In this thesis the research and application actualities of high performance water reducers both in an outside china were introduced in detail,the synthetic methods and debelopment trends of Polycarboxylic acid type high performance water-reducer was analyzed.Though the molecule design,beginning with the chemical structure and antion mechanisms of high performance water-reducers, polycarboxylic acid type water-reducer which contain,hydroxy carboxyl,sulfonic, polyoxyethylene groups and so on with comb-like molecular structure was synthesized.In this paper,using allyl alcohol polyoxyethylene(APEG),acrylic acid(AA),maleic anhydride(MAD),and Sodium methyl acrylamide(SMAS) as the main raw material.By the radical polymerization,the polycarboxylate acid type water-reducers was synthesized with the using of initiator.The experimental structure indicated that,When monomer APEG:AA:MAD:SMAS mole of ratio 3:4:8:3,this copolymer has the good dispersivity.At the same time the best response condition has been determined:the amount of initiator used for the reactant weight 2%;the reanctant concentrationis 25%;the temperature is 85℃; the reaction time is 4h.The studying of FTIR analysis showed that the molecule structure of synthetic product has the carboxylic groups,sulphonic groups,polyoxyethylene side chain groups. Through gathers the Polycarboxylic acid type water-reducer to the synthesis is reduces water medicinal preparation a series of concrete,the cement experiment,finally indicated the self-restraint gathers polycarboxylic acid type water-reducer have the good dispersivity and the dispersive retentivity.The compatibility between PC with cement is excellent.The configuration concrete has the excellent characteristics such as lower slump loss.The water-reducing ratio in concrete was 32.4% at the solid dosage of 0.3%. the strength ratio was 160%.The properties of PC were obviously superior to FDN,so it can be applied at the concrete profession.Through the studying of surface properties such as surface tension of water-reducer concentration, zeta potential and adsorption capacity of water-ruducer onto cement particles of synthetic product,the water-reducing mechanism was exploited.The results indicated that the water-reducing mechanism mainly depends on the adsorption and dispersion of the interactivity between the polycarboxylate superplasticizer and the cement.On one hand,in the mixed system of superplasticizer,water,and cements,the electric double layer is informed while the polycarboxylate superplasticizer is absorbed on the cement,which generated intra-particle repulsion force.On the other hand,the side chain of the polycarboxylate superplasticizer displays steric hindrance because of extension of longer branched chain.So the dispersion and stability of the dispersion is increased significantly.By analyzing the economic function evaluation,this copolymer have certain function and price advantage,so its future in market is great.更多还原