AMPS改性环氧树脂的合成及乳化性质

发布时间：2018-03-26 13:53

  本文选题：环氧树脂　切入点：2-丙烯酰胺基-2-甲基丙磺酸　出处：《中南大学》2005年硕士论文

【摘要】：化学改性法制得的环氧树脂乳液不含小分子表面活性剂,具备自乳化结构,且分散相粒子的尺寸很小,可以达到纳米级,因此备受关注。文献报导的制备阴离子水性环氧树脂的改性剂主要是丙烯酸类单体。羧基被引入到环氧树脂分子链中,再中和成盐使树脂获得水分散性。这种途径得到的环氧树脂乳液在弱碱性条件才能稳定,当pH值改变时乳液体系容易结块与凝胶,不利于储存与使用。 本研究以丙烯酰胺基-2-甲基丙磺酸(AMPS)为水性单体,对环氧树脂进行改性。此共聚物不需中和,就能获得良好的水分散性。设计出了AMPS改性环氧树脂的反应路线,通过正交实验和对比实验,对反应物配比、聚合温度和引发剂用量等反应条件进行了优化,并探讨了影响反应稳定性的因素。由于AMPS的高聚合活性,须采用一些较为特殊的单体滴加方法,以保证共聚反应的稳定进行。结果发现,原料配比环氧树脂:AMPS(摩尔比)为1:2,反应温度为110℃,引发剂用量为1.5%时得到的高聚物收率可达69.1%。测试了反应过程中特性粘数[η]、体系酸值及高聚物的收率随反应时间的变化规律。利用红外光谱表征了共聚物的结构,并对所得乳液的各项稳定性进行了测试,对聚合反应的表观性质进行了描述。 从反应体系的酸值随反应时间下降推测,除了在BPO引发剂作用下AMPS与环氧树脂主链上的接枝反应之外,还有AMPS的磺酸基团与环氧树脂的环氧基的扩链反应发生。于是本论文中进行了三个平行实验,探讨反应的机理。结果发现,整个实验中接枝反应和环氧基的开环反应同时进行,二者在反应的前期和后期分别居于主导地位。从测定高聚物的DSC和TG曲线,有两个玻璃化温度,证实了对反应机理的推断。以反应体系中环氧树脂的浓度变化为对象,用微商法求出了AMPS与环氧树脂反应的总反应和接枝反应的活化能和速率常数,发现环氧树脂分子链上的链自由基产生速率是控制接枝与扩链反应进行的关键。 聚合物乳液的粒径分布和聚合时间有关。随着时间的延长,聚合物乳液的粒径先减小后增大,且分布变宽,原因是反应后期主要发生的是开环反应,消耗了体系中磺酸基,生成了疏水性的磺酸酯基,使AMPS改性环氧树脂的水分散性下降。研究中还发现乳液的粒径与AMPS的用量有密切关系,随着AMPS量的增加,产物水分散体的
[Abstract]:The epoxy emulsion prepared by chemical modification does not contain small molecular surfactants and has self-emulsifying structure, and the size of dispersed particles is very small, which can reach nanometer level. The main modifier for the preparation of anionic waterborne epoxy resin is acrylic monomers. The carboxyl group is introduced into the molecular chain of epoxy resin. The epoxy resin emulsion obtained by neutralization and salt formation can only be stabilized under weak alkaline conditions. When pH value is changed, the emulsion system is easy to agglomerate and gel, which is not conducive to storage and use. In this study, epoxy resin was modified with acrylamide (2-methylpropanesulfonic acid) as waterborne monomer. The copolymers could obtain good water dispersion without neutralization. The reaction route of AMPS modified epoxy resin was designed. By orthogonal and comparative experiments, the reaction conditions such as the ratio of reactants, polymerization temperature and initiator dosage were optimized, and the factors affecting the stability of the reaction were discussed. Some special monomer dropping methods were used to ensure the stability of the copolymerization. It was found that the molar ratio of epoxy resin to epoxy resin was 1: 2 and the reaction temperature was 110 鈩，

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