In the present paper a model equation for calculating the radical desorption rate constant,k<sub>0</sub>,in the emulsion polymerization of vinyl acetate was suggested and the various parameters forevaluati...In the present paper a model equation for calculating the radical desorption rate constant,k<sub>0</sub>,in the emulsion polymerization of vinyl acetate was suggested and the various parameters forevaluating k<sub>0</sub> were determined.Effects of reaction temperature,emulsifier concentration,initiator con-centration,monomer conversion and phase ratio on k<sub>0</sub> were studied.It indicates that the desorptionof radicals from latex particles to aqueous phase must be taken into account in the modelling ofemulsion polymerization for the monomers with higher hydrophilicity such as vinyl acetate.展开更多
The behaviour of water soluble and monomer soluble inhibitors in the emulsion polymerization for CaseI system(e.g.vinyl acetate and vinyl chloride)has been studied.The behaviour of monomer soluble inhibitorsis shown t...The behaviour of water soluble and monomer soluble inhibitors in the emulsion polymerization for CaseI system(e.g.vinyl acetate and vinyl chloride)has been studied.The behaviour of monomer soluble inhibitorsis shown to be quite different from that observed in Case Ⅱ emulsion polymerization system.Model predictionsof the effect of these inhibitors on polymer particle nucleation and growth rate are shown to be in satisfactoryagreement with experimental results.展开更多
Poly (acrylonitrile-co-vinyl acetate)/polypyrrole composite particles with uniform size and morphology have been synthesized using one-step polymerization that involves swelling and coating of polypyrrole (PPy) into P...Poly (acrylonitrile-co-vinyl acetate)/polypyrrole composite particles with uniform size and morphology have been synthesized using one-step polymerization that involves swelling and coating of polypyrrole (PPy) into P (AN-co-VAc) latex nanoparticles. As an initial stage, free radical copolymerization of acrylonitrile (AN) and vinyl acetate (VAc) was synthesized by emulsion polymerization using ammonium persulfate (APS) and dodecyl benzene sulfonic acid salt (DBSA) as a surfactant. P (AN-co-VAc)/PPy composites were obtained first time by in situ addition of the pyrrole into the reaction medium. The electrospun P (AN-co-VAc)/PPy nanofibers were obtained from the nanoparticles with better properties and the effect of PPy on the morphology of nanofibers was studied by scanning electron microscopy (SEM). High degree of homogeneity and molecular order induced by molecular dispersion of polypyrrole on copolymer matrix without phase separation improve the transport properties and stability of polypyrrole, which are critical for high-performance organic electronics.展开更多
基金Supported by the National Natural Science Foundation of China
文摘In the present paper a model equation for calculating the radical desorption rate constant,k<sub>0</sub>,in the emulsion polymerization of vinyl acetate was suggested and the various parameters forevaluating k<sub>0</sub> were determined.Effects of reaction temperature,emulsifier concentration,initiator con-centration,monomer conversion and phase ratio on k<sub>0</sub> were studied.It indicates that the desorptionof radicals from latex particles to aqueous phase must be taken into account in the modelling ofemulsion polymerization for the monomers with higher hydrophilicity such as vinyl acetate.
文摘The behaviour of water soluble and monomer soluble inhibitors in the emulsion polymerization for CaseI system(e.g.vinyl acetate and vinyl chloride)has been studied.The behaviour of monomer soluble inhibitorsis shown to be quite different from that observed in Case Ⅱ emulsion polymerization system.Model predictionsof the effect of these inhibitors on polymer particle nucleation and growth rate are shown to be in satisfactoryagreement with experimental results.
文摘Poly (acrylonitrile-co-vinyl acetate)/polypyrrole composite particles with uniform size and morphology have been synthesized using one-step polymerization that involves swelling and coating of polypyrrole (PPy) into P (AN-co-VAc) latex nanoparticles. As an initial stage, free radical copolymerization of acrylonitrile (AN) and vinyl acetate (VAc) was synthesized by emulsion polymerization using ammonium persulfate (APS) and dodecyl benzene sulfonic acid salt (DBSA) as a surfactant. P (AN-co-VAc)/PPy composites were obtained first time by in situ addition of the pyrrole into the reaction medium. The electrospun P (AN-co-VAc)/PPy nanofibers were obtained from the nanoparticles with better properties and the effect of PPy on the morphology of nanofibers was studied by scanning electron microscopy (SEM). High degree of homogeneity and molecular order induced by molecular dispersion of polypyrrole on copolymer matrix without phase separation improve the transport properties and stability of polypyrrole, which are critical for high-performance organic electronics.
文摘采用种子乳液聚合,引入乙烯基三甲氧基硅烷(A-171),以十二烷基苯磺酸钠(DSB)和壬基酚聚氧乙烯(20)醚(OP-10)作复合乳化剂,以过硫酸钾(KPS)为引发剂,在反应温度为78±2 ℃条件下,合成了A-171改性醋酸乙烯酯(VAc)-丙烯酸酯共聚乳液.实验采用单体滴加工艺,考察了配方中丙烯酸丁酯(BA)、甲基丙烯酸(MAA)和A-171用量对共聚物性能和乳液聚合过程的影响,并用红外光谱仪(FTIR)、粒度仪和差示量热扫描仪(DSC)对共聚物的结构及性能进行了表征.结果表明,引入w(BA)=10%～15%(相对于配方中单体总质量,下同)、w(MAA)=4%、w(A-171)=1%到VAc -丙烯酸酯共聚物乳液中,共聚物乳液涂膜的吸水率<5.0%,耐寒性通过10个循环,60 ℃加速贮存稳定性>100 d.
