在醋酸乙烯含量低的乙烯-醋酸乙烯共聚物(EVA)中掺入甲基乙烯基硅氧烷进行混炼改性。确定了硅氧烷加入量,混炼时间和温度等改性条件。熔融热的差热分析表明,改性可降低 EVA 的结晶度。改性后左炔诺孕酮、醋酸甲地孕酮和黄体酮在聚合物...在醋酸乙烯含量低的乙烯-醋酸乙烯共聚物(EVA)中掺入甲基乙烯基硅氧烷进行混炼改性。确定了硅氧烷加入量,混炼时间和温度等改性条件。熔融热的差热分析表明,改性可降低 EVA 的结晶度。改性后左炔诺孕酮、醋酸甲地孕酮和黄体酮在聚合物中的溶解度和扩散系数均有提高,寻致通透性增加。展开更多
Critical association concentration (Ca) of ethylene-vinyl acetate copolymer (EVA) in selective solvent mixtures of 1,2-dichloroethane (DCE) (polar solvent) and cyclohexane (CYH) (non-polar solvent) was investigated. D...Critical association concentration (Ca) of ethylene-vinyl acetate copolymer (EVA) in selective solvent mixtures of 1,2-dichloroethane (DCE) (polar solvent) and cyclohexane (CYH) (non-polar solvent) was investigated. DCE is a good solvent for polyvinyl acetate (PVAc) and a poor solvent for paraffin, whereas CYH is a good solvent for the paraffin and a precipitant for PVAc. Viscosities of EVA in different compositions of the solvent mixture with and without additives were measured. Viscosity results were used to determine the C-A value of the systems. It is shown that C-A was markedly dependent on the composition of the solvent mixture and concentration and structure of the additive. Solvation and competition between hydrogen bonding and micellisation were suggested for qualitative description of the changing of C-A value observed.展开更多
基金The project was supported by National Natural Science Foundation of China(No.29774020).
文摘Critical association concentration (Ca) of ethylene-vinyl acetate copolymer (EVA) in selective solvent mixtures of 1,2-dichloroethane (DCE) (polar solvent) and cyclohexane (CYH) (non-polar solvent) was investigated. DCE is a good solvent for polyvinyl acetate (PVAc) and a poor solvent for paraffin, whereas CYH is a good solvent for the paraffin and a precipitant for PVAc. Viscosities of EVA in different compositions of the solvent mixture with and without additives were measured. Viscosity results were used to determine the C-A value of the systems. It is shown that C-A was markedly dependent on the composition of the solvent mixture and concentration and structure of the additive. Solvation and competition between hydrogen bonding and micellisation were suggested for qualitative description of the changing of C-A value observed.
