【作者】 徐俊；

【导师】 俞马宏；

【作者基本信息】 南京理工大学 ， 化学工程， 2012， 硕士

【摘要】 聚醋酸乙烯酯由于成本较低、绿色环保、粘接强度高,但具有较强的吸水性从而使其应用受到限制。本论文研究分别从乳化剂、保护胶体等方面入手,考察其对聚醋酸乙烯酯乳液稳定性以及耐水性的影响,然后采用共聚改性、无皂聚合以及共混改性的方法改善聚醋酸乙烯酯乳液的耐水性。论文首先考察保护胶体(PVA)、阴离子乳化剂、非离子乳化剂以及阴离子/非离子复合乳化剂对乳液稳定性、吸水率以及乳胶粒粒径的影响。得出了PVA能够调节乳液的黏度,并且能够提高乳液的稳定性,但用量过大,乳液的吸水率逐渐增大。采用复合乳化剂有利于乳液的稳定性,并且随着乳化剂用量的增大乳胶粒粒径逐渐减小。其次讨论了引发剂用量对乳液性能的影响,得出了引发剂用量过少或者过多都不利于聚合反应的进行。第三,通过不同的单体与醋酸乙烯酯共聚,对乳液进行改性。通过正交实验考查不同单体的配比对共聚乳液性能的影响,得到了粘接强度高,耐水性好的共聚乳液。第四,通过无皂聚合改性聚醋酸乙烯酯乳液。由于在聚合过程中不加乳化剂,乳液的稳定性差,本章采用亲水性的马来酸作功能性单体并加入丙烯酸丁酯与醋酸乙烯酯共聚共聚得到了稳定性好、吸水率低的无皂共聚乳液。最后采用丙烯酸羟乙酯与醋酸乙烯酯共聚,然后加入MDI进行共混改性。由于MDI能够和共聚物上的羟基与聚乙烯醇上的羟基反应,形成网状的大分子结构所以乳液的耐水性与拉伸剪切强度都得到了很大的提高。通过粒径扫描仪、红外光谱仪、拉伸强度仪、透射电镜等仪器对乳液进行测试表征,得出改性后的聚醋酸乙烯酯乳液各项性能都得到了很大的提高。更多还原

【Abstract】 Polyvinyl acetate emulsion has advantage of low cost, enviromental protection, high bonding strength, but disadvantage of poor water resistance. From emulsifier, protective colloid, the reasons for poor water resistance are analyzed. The methods of improving the water resistance of polyvinyl acetate are discussed, such as copolymerization with vinyl acetate, addition of compounding agent and emulsifier-free emulsion polymerization.Firstly, the paper studies the influence of PVA and different emulsifiers on polymerization and performance of polyvinyl acetate emulsion. Discuss the influence of emulsifier on particle size, water resistance and stability of polyvinyl acetate emulsion. The studies show the dosage of PVA is big the emulsion has good performance but disadvantage of water resistance. Using complex emulsifier the storage stability increased. As increasing complex emulsifier content particle size became smaller.Secondly, studies the influence of initiator dosage on performance of polyvinyl acetate emulsion. The studies show too little or too much initiator dosage disadvantage of reaction stability.Thirdly, seleceting three monmers as modifiers, the modification which was optimized with orthogonal design, lastly gained a emulsion with excellent water resistance and tensile strength.Fourthly, the copolymer of polyvinyl acetate was prepared by emulsifier-free emulsion process. As there is no emulsifier in the polymerization process, the stability of emulsion was poor. This chapter has described the soap-free copolymerization with vinyl acetate as basic monomer, maleic acid as modification functional monomer and butyl acrylate as modifier monomer, forming a stable, good water resistance emulsion.Finally, the copolymer of vinyl acetate and hydroxyethyl acrylate was synthesized by emulsion polymerization and then added the MDI. As the MDI can react with the hydroxyl groups of copolymers and the hydroxyl groups of polyvinyl alcohol, which made water resistance and tensile strength of the emulsion greatly improved.It was demonstrated that the properties of modified polyvinyl acetate had been improved greatly through the tests of particle size analyzer, tensile strength, FTIR, TEM, and so on.更多还原