發(fā)布時(shí)間：2019-07-07 19:36

【摘要】：聚羧酸減水劑(Polycarboxylate Superplasticizer)作為新一代減水劑,由于其較高的減水率、較好的保坍性、較好的水泥適應(yīng)性以及環(huán)境友好性已成為當(dāng)今混凝土減水劑的發(fā)展方向。但是,隨著建筑行業(yè)要求的不斷提高以及混凝土技術(shù)的發(fā)展,聚羧酸減水劑逐漸暴露出一些問題,例如粘土對(duì)聚羧酸減水劑分散作用的損害等。因此,本文旨在研究出一種新型的聚羧酸減水劑以對(duì)今后減水劑實(shí)際合成與應(yīng)用方面提供指導(dǎo)。本文根據(jù)梳形聚羧酸減水劑的分子結(jié)構(gòu)、吸附與減水機(jī)理以及合成工藝結(jié)合原子轉(zhuǎn)移自由基聚合(Atom Transfer Radical Polymerization,ATRP)的優(yōu)點(diǎn),采用四步法合成了一種含有三臂結(jié)構(gòu)的聚羧酸減水劑(Three-Arm Polycarboxylate Superplasticizer,TAPCE)。第一步,以三羥甲基丙烷(TMP)為核分子制備具有三官能團(tuán)的小分子引發(fā)劑(Br-TMP-Br);第二步,以小分子引發(fā)劑引發(fā)丙烯酸叔丁酯(tBA)合成三臂聚羧酸減水劑的第一嵌段(PtBA);第三步,利用第二步合成的第一嵌段繼續(xù)引發(fā)烯丙基聚氧乙烯醚(HPEG)聚合得到第二嵌段(P(tBA-HPEG));第四步,將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減水劑。通過實(shí)驗(yàn)探究表明,當(dāng)大單體選用HPEG 3000,2-溴代異丁酰溴與三羥甲基丙烷最佳的摩爾比為:BIBB/TMP=3.2:1.0,兩種單體與引發(fā)劑的比例為tBA:HPEG:Br-TMP-Br=60.49:8.93:1.0時(shí),合成的三臂聚羧酸減水劑具有良好的分散及分散保持性。對(duì)合成的三臂聚羧酸減水劑按照相關(guān)的測(cè)試標(biāo)準(zhǔn)進(jìn)行測(cè)試,并與常規(guī)梳形工業(yè)樣品進(jìn)行對(duì)比,TAPCE在凈漿分散及分散保持性、砂漿分散及分散保持性、砂漿減水率與力學(xué)性能測(cè)試上均表現(xiàn)出優(yōu)異的性能。尤其值得注意的是,相對(duì)于梳形減水劑,TAPCE具有優(yōu)異的抗泥性能,使含有1%膨潤(rùn)土的水泥凈漿流動(dòng)度達(dá)到260±5 mm時(shí),TAPCE用量?jī)H為常規(guī)減水劑的80%甚至更少。
文內(nèi)圖片：
圖片說明：聚羧酸減水劑空間位阻作用示意圖
[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 鹵5 mm, the amount of TAPCE is only 80% or even less than that of conventional water reducer.
【學(xué)位授予單位】：濟(jì)南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU528.042.2

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