一种三臂聚羧酸高效减水剂的制备与性能研究

发布时间：2019-07-07 19:36

【摘要】：聚羧酸减水剂(Polycarboxylate Superplasticizer)作为新一代减水剂,由于其较高的减水率、较好的保坍性、较好的水泥适应性以及环境友好性已成为当今混凝土减水剂的发展方向。但是,随着建筑行业要求的不断提高以及混凝土技术的发展,聚羧酸减水剂逐渐暴露出一些问题,例如粘土对聚羧酸减水剂分散作用的损害等。因此,本文旨在研究出一种新型的聚羧酸减水剂以对今后减水剂实际合成与应用方面提供指导。本文根据梳形聚羧酸减水剂的分子结构、吸附与减水机理以及合成工艺结合原子转移自由基聚合(Atom Transfer Radical Polymerization,ATRP)的优点,采用四步法合成了一种含有三臂结构的聚羧酸减水剂(Three-Arm Polycarboxylate Superplasticizer,TAPCE)。第一步,以三羟甲基丙烷(TMP)为核分子制备具有三官能团的小分子引发剂(Br-TMP-Br);第二步,以小分子引发剂引发丙烯酸叔丁酯(tBA)合成三臂聚羧酸减水剂的第一嵌段(PtBA);第三步,利用第二步合成的第一嵌段继续引发烯丙基聚氧乙烯醚(HPEG)聚合得到第二嵌段(P(tBA-HPEG));第四步,将第三步得到的聚合物置于三氟乙酸水溶液中水解得到三臂聚羧酸减水剂。通过实验探究表明,当大单体选用HPEG 3000,2-溴代异丁酰溴与三羟甲基丙烷最佳的摩尔比为:BIBB/TMP=3.2:1.0,两种单体与引发剂的比例为tBA:HPEG:Br-TMP-Br=60.49:8.93:1.0时,合成的三臂聚羧酸减水剂具有良好的分散及分散保持性。对合成的三臂聚羧酸减水剂按照相关的测试标准进行测试,并与常规梳形工业样品进行对比,TAPCE在净浆分散及分散保持性、砂浆分散及分散保持性、砂浆减水率与力学性能测试上均表现出优异的性能。尤其值得注意的是,相对于梳形减水剂,TAPCE具有优异的抗泥性能,使含有1%膨润土的水泥净浆流动度达到260±5 mm时,TAPCE用量仅为常规减水剂的80%甚至更少。
文内图片：

图片说明：聚羧酸减水剂空间位阻作用示意图
[Abstract]:(Polycarboxylate Superplasticizer), as a new generation of water reducer, has become the development direction of concrete water reducer because of its high water reduction rate, good collapse retention, good cement adaptability and environmental friendliness. However, with the continuous improvement of the requirements of the construction industry and the development of concrete technology, some problems have been gradually exposed, such as the damage of clay to the dispersion of polycarboxylic acid water reducer, and so on. Therefore, the purpose of this paper is to develop a new type of polycarboxylic acid water reducer to provide guidance for the actual synthesis and application of water reducer in the future. According to the molecular structure, adsorption and water reduction mechanism of comb polycarboxylic acid water reducer and the advantages of synthesis process combined with atom transfer radical polymerization (Atom Transfer Radical Polymerization,ATRP), a kind of polycarboxylic acid water reducer (Three-Arm Polycarboxylate Superplasticizer,TAPCE) with three-arm structure was synthesized by four-step method. In the first step, the small molecular initiator (Br-TMP-Br) with trifunctional groups was prepared by using trimethylolpropane (TMP) as nuclear molecule, and the second step was the first block (PtBA); with tert-butyl acrylic acid (tBA) initiated by small molecular initiator, and the second block (P (tBA-HPEG); was obtained by the polymerization of allyl polyoxylene ether (HPEG) with the first block synthesized in the second step. In the fourth step, the polymer obtained in the third step was hydrolyzed in trifluoroacetic acid aqueous solution to obtain triarm polycarboxylic acid water reducer. The experimental results show that when the macromonomer HPEG 3000, the optimum molar ratio of 2-bromoisobutyryl bromide to trimethylol propane is tBA:HPEG:Br-TMP-Br=60.49:8.93:1.0, the synthesized three-arm polycarboxylic acid water reducer has good dispersion and dispersion retention when the ratio of BIBB/TMP=3.2:1.0, to initiator is tBA:HPEG:Br-TMP-Br=60.49:8.93:1.0. The synthesized three-arm polycarboxylic acid water reducer was tested according to the relevant test standards and compared with the conventional comb industrial samples. TAPCE showed excellent properties in the dispersion and retention of pulp, water reduction rate and mechanical properties of mortar. It is particularly worth noting that compared with comb water reducer, TAPCE has excellent mud resistance. When the mobility of cement paste containing 1% bentonite reaches 260 卤5 mm, the amount of TAPCE is only 80% or even less than that of conventional water reducer.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528.042.2

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