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采用预乳化-半连续乳液聚合方法制备了不同单体比例的甲基丙烯酸甲酯(MMA)/甲基丙烯酸(MAA)二元共聚物乳液。研究了甲基丙烯酸含量对乳液羧基分布的影响,结果表明,随着甲基丙烯酸含量增大,乳液中水相、乳胶粒子表面、内部的羧基含量都增加,水相中增加趋势最大,乳胶粒子表面增加趋势最小。利用凝胶渗透色谱(GPC),红外光谱(FT-IR),热分析方法(TG)对乳液共聚物分子量及分子量分布、聚合物结构、热稳定性进行研究,研究表明聚合物Mw在2.007×105～2.321×105之间,分子量分布为1.288～1.462,其热分解温度375～480℃,且热稳定性随甲基丙烯酸含量增大而有所提高。
A series of emulsions of MMA / MAA binary copolymers with different monomer ratios were prepared by pre-emulsion-semi-continuous emulsion polymerization. The effects of methacrylic acid content on the carboxyl distribution of the emulsion were studied. The results showed that with the increase of the content of methacrylic acid, the content of carboxyl groups in the aqueous phase and latex particles in the emulsion increased, while the content in the aqueous phase increased most. The trend of increasing the surface is the smallest. The molecular weight, molecular weight distribution, polymer structure and thermal stability of emulsion copolymer were investigated by gel permeation chromatography (GPC), infrared spectroscopy (FT-IR) and thermal analysis (TG). The results showed that the Mw of polymer was 2.007 × 105 ~ 2.321 × 105, the molecular weight distribution is 1.288 ~ 1.462, the thermal decomposition temperature is 375 ~ 480 ℃, and the thermal stability increases with the increase of methacrylic acid content.