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Conventional emulsion and miniemulsion homopolymerization and copolymerization of vinyl acetate and vinyl 2-ethylhexanoate monomers.

机译:乙酸乙烯酯和2-乙基己酸乙烯酯单体的常规乳液和细乳液均聚和共聚。

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摘要

For monomers possessing significantly low water solubility (V2EH), miniemulsion polymerization can substantially enhance the reaction kinetics compared to conventional emulsion systems. While the monomer droplets in a conventional emulsion only serve as reservoirs supplying monomer, diffusional restrictions of the monomer to get to the site of nucleation and the growing particles effectively slows the reaction. For miniemulsions, the monomer is already at the site of nucleation and growth; and therefore, is not as severely afflicted.;When using reactive TREM LF-40 versus its nonreactive, hydrogenated derivative, trends comparing VAc and V2EH conventional emulsion homopolymerization kinetics display that the chain transfer to the surfactant retards the reaction. This effect was not as prevalent in the miniemulsion systems, which was attributed to larger particles being generated. The miniemulsion particles' surface-to-volume is less compared to conventional emulsions; therefore, the role TREM LF-40 plays in slowing the reaction is diminished.;The polymeric version of TREM is also a reasonably good surfactant in both conventional and miniemulsion homopolymerization. Although a nonreactive form without allylic functionality, increasing poly(TREM) concentration lead to slower kinetics. This result is attributed to the polymeric surfactant sitting on the outside of the particle and effectively behaving as a barrier to radical entry.;Copolymerization showed V2EH incorporates well with VAc. Kinetics studies indicated that varying the monomer ratio did not affect the miniemulsion system as significantly compared to conventional emulsion copolymerization, which was attributed to V2EH monomer's low water solubility. VAc's higher water solubility is suspected to facilitate V2EH's transport through the aqueous phase; therefore, enhancing the kinetics as the VAc component is increased. Additionally, miniemulsion copolymerization has each monomer already present at the site of nucleation and growth; therefore, little is gained as the comonomer ratio is altered.;Miniemulsion copolymerization also resulted in better incorporation of the two monomers. Increased alkaline stability of the miniemulsion copolymers stems from having the two monomers forced to copolymerize at the same location. VAc has the potential to more readily homopolymerize in the aqueous phase than does V2EH; therefore, in conventional copolymerization a significant component of the final latex product richer in VAc content exists.
机译:对于具有显着低的水溶性(V2EH)的单体,与常规乳液体系相比,细乳液聚合可以大大提高反应动力学。虽然常规乳液中的单体液滴仅用作供应单体的容器,但单体的扩散限制会到达成核位置,并且生长的颗粒有效地减慢了反应。对于细乳液,单体已经处于成核和生长的位置。当使用反应性TREM LF-40与非反应性氢化衍生物相比时,比较VAc和V2EH常规乳液均聚动力学的趋势表明,链转移至表面活性剂会阻碍反应。这种作用在细乳液体系中并不普遍,这归因于产生了较大的颗粒。细乳液颗粒的表面体积比常规乳液要小。因此,TREM LF-40在减慢反应中所起的作用被减弱了。TREM的聚合形式在常规乳液和细乳液均聚中也是一种相当好的表面活性剂。尽管没有烯丙基官能团的非反应形式,但聚(TREM)浓度的增加导致动力学变慢。该结果归因于聚合物表面活性剂位于颗粒的外部,并且有效地充当了自由基进入的屏障。共聚表明V2EH与VAc很好地结合。动力学研究表明,与常规乳液共聚相比,改变单体比例不会显着影响细乳液体系,这归因于V2EH单体的低水溶性。怀疑VAc较高的水溶性,可促进V2EH通过水相的运输。因此,随着VAc组分的增加,动力学增强。另外,细乳液共聚使每种单体已经存在于成核和生长的位置。因此,随着共聚单体比例的改变,收效甚微。细乳液共聚还可以使两种单体更好地结合。细乳液共聚物碱稳定性的提高是由于迫使两种单体在同一位置共聚。 VAc比V2EH具有更容易在水相中均聚的潜力;因此,在常规共聚中,存在最终乳胶产品的重要组分,其富含VAc含量。

著录项

  • 作者

    Kitzmiller, Ervin Lloyd.;

  • 作者单位

    Lehigh University.;

  • 授予单位 Lehigh University.;
  • 学科 Chemistry Polymer.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 266 p.
  • 总页数 266
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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