【作者】 陈刚；

【导师】 雷家珩；

【作者基本信息】 武汉理工大学 ， 应用化学， 2009， 硕士

【摘要】 聚羧酸系高效减水剂对混凝土性能的提高有极其重要的作用,目前已经被广泛应用。其中,聚马来酸酐减水剂因其性能优异,是目前研究与应用的重要方向之一。国外对聚马来酸酐减水剂的研究技术已经比较成熟,而国内因国外技术保密、科研技术相对落后等因素,产品性能与国外还有较大的差距。研究表明聚马来酸酐减水剂的合成过程中,其关键技术包括:具有聚合活性的大分子单体的制备;聚合条件对三元共聚反应的影响;聚合产物中各基团的比例对减水剂性能的影响等。针对上述关键技术,我们开展了以下三方面的工作:(1)以丙烯酸(AA)、聚乙二醇(PEG)、聚乙二醇单甲醚(MPEG)为原料,通过酯化反应制备了具有聚合活性的大单体,考察了合成条件以及影响大单体性能的因素。结果表明,酯化反应条件对不同端基PEG酯化反应的影响趋势一致,由PEG和AA酯化反应制备的大单体中因含有副产物双酯,其性能要劣于由MPEG和AA酯化反应制备的大单体的性能。(2)以马来酸酐(MA)、甲基丙烯磺酸钠(MAS)、由MPEG和AA酯化反应制备的大单体为原料,通过三元共聚反应合成了聚马来酸酐高效减水剂,考察了聚合条件对聚合产物结构和性能的影响。结果表明,随着聚合温度的升高,减水剂的水泥净浆流动和聚合产物的分子量都呈先增大后减小的趋势;随着聚合时间的增长,减水剂的水泥净浆流动度呈先增长后逐渐稳定的趋势,聚合产物分子量则基本保持不变;随着引发剂浓度的增长,减水剂的水泥净浆流动度呈先增长后减小的趋势发展,聚合产物分子量则一直减小。(3)通过改变单体配比,合成了具有不同功能基团比例的聚马来酸酐高效减水剂,分别考察了各基团比例的变化对减水剂性能的影响。结果表明,磺酸基比例的增加,增强了链转移作用,使减水剂的水泥净浆流动度先增大后减小;大单体比例的增加,增加了聚合产物的空间位阻作用,也使减水剂的水泥净浆流动度先增大后减小。当MA的摩尔分数为0.5～0.65,MAS的摩尔分数为0.05～0.15,大单体的摩尔分数为0.3～0.35,MPEG的分子量为1000时,所得聚合产物的减水性能较好,在减水剂掺量为0.2%、水灰比为0.29的情况下,水泥净浆流动度达到307mm,此时聚合产物的分子量为1.28×10~4。更多还原

【Abstract】 Polycarboxylate superplasticizer has an important role on the improvement of concrete performance,it has been widely used at present.Among in which,as a result of a better solution to loss of concrete slump,Polymaleic Anhydride Superplasticizer is one of the important direction on research and application at the moment.But in the synthesis process of Polymaleic Anhydride Superplasticizer,it exist these problems below.First,macromer with polymerization activity is not easy preparated.Second,the effects of polymerization conditions on ternary copolymerization is not clear.Third, the effects of the proportion of each group in polymerization product on superplasticizer performance is not clear.In response to the issues above,we carried out the work of the following three aspects:（1） To acrylic acid（AA）、polyethylene glycol（PEG） and methoxy polyethylene glycol（MPEG）as raw materials,we preparates macromer with polymerization activity by esterification,investigates synthesis conditions and factors which impact on the properties of macromer.Based on these experimental results,esterification reaction conditions have the same effects on esterification by different terminal group of PEG.;the performance of macromer containing diester preparated by the esterification of PEG and AA,is worse than that preparated by the esterification of MPEG and AA.（2） To maleic anhydride（MA）、sodium methyl-acrylamide（MAS） and macromer preparated by the esterification of MPEG and AA as raw materials,we preparates Polymaleic Anhydride Superplasticizer by ternary copolymerization,investigates the effect of polymerization conditions on the structure and properties of polymerization products.Based on these experimental results,as the polymerization temperature increasing,fluidity of cement paste of superplasticizer and the molecular weight of polymer product increase at first and then decrease;As the polymerization time increasing,fluidity of cement paste of superplasticizer increases at first and then stabilizes gradually,and the molecular weight of polymer product remains basically unchanged;As the concentration of initiator increasing,fluidity of cement paste of superplasticizer increases at first and then decreases,and the molecular weight of polymer product decreases all along.（3） we preparates acrylic block of Superplasticizer Polymaleic Anhydride with different proportion of functional groups,by changing the ratio of monomers, investigates the effect of the changes of each group proportion on properties of polymerization products.Based on these experimental results,As the proportion of—SO₃^- increasing,the role of chain transfer enhanced,the fluidity of cement paste of superplasticizer increases at first and then decreases;As the proportion of macromer increasing,the role of the steric hindrance of polymerization product enhanced,the fluidity of cement paste of superplasticizer increases at first and then decreases too.When the mole fraction of MA between 0.5 and 0.65,the mole fraction of MAS between 0.05 and 0.15,the mole fraction of macromer between 0.3 and 0.35,the molecular weight of MPEG is 1000,polymerization products obtain the best performance of fluidity of cement paste.When the content of superplasticizer is 0.2%,water-cement ratio is 0.29,the fluidity of cement paste reach at 307mm,At this point the molecular weight of polymerization product is 1.28×10⁴.更多还原