本文選題：聚羧酸減水劑　切入點(diǎn)：RAFT法　出處：《華南理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：聚羧酸減水劑(PCEs)具有減水率高、保坍性好、分子結(jié)構(gòu)可設(shè)計(jì)性強(qiáng)和節(jié)能環(huán)保等特點(diǎn),一經(jīng)問(wèn)世便得到迅速發(fā)展,目前在中國(guó)已經(jīng)占據(jù)了超過(guò)一半的減水劑市場(chǎng)份額。PCEs的合成一直采用自由基聚合的方法,該方法合成的聚合物分子量分布較寬(多分散性PDI1.5),研究分子量與性能之間的關(guān)系時(shí)缺乏說(shuō)服力。可逆加成-斷裂鏈轉(zhuǎn)移聚合(RAFT)是一種比較新的可控/活性聚合方法,合成的聚合物分子量分布窄、分子量大小易調(diào)節(jié),目前主要應(yīng)用于非水溶性的星型、梳型等結(jié)構(gòu)特殊的聚合物合成中,在合成水溶性聚合物方面應(yīng)用較少。PCEs是一種水溶性交聯(lián)接枝聚合物,對(duì)聚合條件的要求更為特殊。本文根據(jù)RAFT法可控聚合的原理,合成出不同分子量及分子量分布的PCEs,探討了合成工藝影響因素,并考察了分子量及分子量分布對(duì)其應(yīng)用性能的影響規(guī)律。主要的研究?jī)?nèi)容及結(jié)果如下:1、合成S-S'-二(a,a'-二甲基-a"-乙酸)-三硫代碳酸酯(BDATT)RAFT試劑,以現(xiàn)有常用原料合成PCEs,通過(guò)考察聚合溫度、小單體與RAFT試劑共同滴加時(shí)間、引發(fā)劑滴加時(shí)間等參數(shù)對(duì)分子量分布及單體轉(zhuǎn)化率的影響規(guī)律,優(yōu)化RAFT法合成PCEs的聚合工藝。本聚合系統(tǒng)中,聚合溫度為80℃,引發(fā)劑水溶液與BDATT的丙烯酸水溶液同時(shí)滴加3h的條件下得到的PCEs單體轉(zhuǎn)化率高(75%以上)且分子量分布窄(多分散性普遍低于1.3)。2、考察不同種類引發(fā)劑、引發(fā)劑摻量、引發(fā)劑與RAFT試劑的摻量比例對(duì)PCEs分子量參數(shù)的影響規(guī)律。偶氮二異丁基脒二鹽酸鹽(AIBA)引發(fā)合成的PCEs比同條件下過(guò)硫酸銨(APS)引發(fā)聚合的PCEs分子量分布更窄且單體轉(zhuǎn)化率更高;同等RAFT試劑摻量下,引發(fā)劑濃度越高,PCEs分子量分布越寬,單體轉(zhuǎn)化率越高;改變引發(fā)劑與RAFT試劑的摻量比發(fā)現(xiàn)隨著RAFT試劑濃度的升高,聚合物的分子量分布變窄,分子量逐漸減小。3、對(duì)RAFT法合成的不同分子量和不同分子量分布的PCEs進(jìn)行應(yīng)用性能測(cè)試,結(jié)果表明分子量大小對(duì)水泥凈漿流動(dòng)度、水泥膠砂減水率、水泥砂漿擴(kuò)展度及水泥砂漿含氣量影響很大。本聚合系統(tǒng)合成的PCEs樣品多分散性系數(shù)(PDI)均小于1.35,在該條件下,具有最佳的凈漿流動(dòng)性及流動(dòng)保持性能的PCEs重均分子量(Mw)大約在81000至89000之間,膠砂減水率最高的PCEs重均分子量大約在80000到100000之間,具有最佳砂漿擴(kuò)展度的PCEs重均分子量大約在70000至88000之間,基本確定具有最佳應(yīng)用性能的PCEs重均分子量在80000至88000之間。砂漿含氣量隨分子量的降低逐漸升高,分子量越大的PCEs經(jīng)時(shí)損失越小。分子量相同時(shí),分子量分布窄的PCEs分散性能更優(yōu)。
[Abstract]:Polycarboxylic acid water reducer (PCEs) has the characteristics of high water reducing rate, good collapsibility, strong design of molecular structure, energy saving and environmental protection. At present, more than half of the market share of water reducers. PCEs have been synthesized by free radical polymerization in China. The polymer synthesized by this method has a wide molecular weight distribution (polydispersity PDI 1.5), which is not persuasive in studying the relationship between molecular weight and properties. Reversible addition-break chain transfer polymerization (Raft) is a new controllable / active polymerization method. The molecular weight distribution of the synthesized polymers is narrow, and the molecular weight is easy to adjust. At present, the synthesized polymers are mainly used in the synthesis of insoluble star and comb polymers with special structure. The application of PCEs in the synthesis of water-soluble polymers is less. PCEs is a kind of water-soluble crosslinked grafted polymers, and the conditions of polymerization are more special. In this paper, according to the principle of controllable polymerization by RAFT method, PCEs with different molecular weight and molecular weight distribution were synthesized. The effects of molecular weight and molecular weight distribution on its application properties were investigated. The main research contents and results were as follows: 1. The synthesis of S-Sz-dimethyl-a "-dimethyl-a" -trithiocarbonate BDATTURAFT reagent, the main research contents and results were as follows. PCEs were synthesized from common raw materials. The influence of polymerization temperature, the time of dropping small monomer and RAFT reagent and the time of initiator dropping on the molecular weight distribution and monomer conversion were investigated. The polymerization process of PCEs was optimized by RAFT method. In this polymerization system, the polymerization temperature was 80 鈩，

本文編號(hào)：1632265