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Aspects of Film Formation from Bimodal Latexes.

机译：双峰乳胶成膜方面。

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摘要

The main goal of this work is to further the molecular level understanding of the film formation process, employing a model system of bimodal latexes. The properties of the two latexes, such as particle sizes, molecular weights, crosslinking densities as well as the functional components, are varied independently.;A self-assembled close-packed morphology was observed in bimodal polystyrene latex blends at an optimum blend ratio, which can be calculated as a function of particle size ratio based on the theory of continuity. It has been found that bimodal particle packing can greatly reduce the void content inside latex films. The film formation process required much less time to complete in a well-blended film than in an unblended film.;Polystyrene particles with different molecular weights were synthesized, and the tensile strengths of films made from these latexes were compared. It was found that the tensile strength increased with molecular weight until it reached a maximum, and then it became independent of molecular weight. The molecular weight (weight-average), rather than the particle size, was the dominant factor in determining a film's mechanical strength.;Crosslinked latexes were mixed together with non-crosslinked latex particles. The corresponding blended film exhibited clear improvements in strength over the unblended non-crosslinked latex films, when the non-crosslinked polymer chains were not long enough to make sufficient entanglements by themselves at the interface.;The experimental results were compared to the theoretical models to examine the competition between polymer interdiffusion and a crosslinking reaction in films comprised of polystyrene reactive latex blends, in which the reactive groups (carboxylic acid and primary amine) were incorporated in separate latex particles. By controlling the molecular parameters we were able to design the film formation process to be reaction controlled, so that the corresponding mechanical properties of the films, such as film modulus, tensile strength and toughness, could be enhanced. A model based on theories and verified against the experimental data was established, which could provide useful guidelines for film interface strengthening with potential applications in the coatings industry.
机译：这项工作的主要目的是通过使用双峰乳胶模型系统来进一步了解成膜过程的分子水平。两种胶乳的性质，例如粒径，分子量，交联密度以及功能组分均独立变化。;在最佳混合比下，双峰聚苯乙烯胶乳共混物中观察到了自组装的紧密堆积形态。可以根据连续性理论将其计算为粒度比的函数。已经发现，双峰颗粒堆积可以大大降低乳胶膜内部的空隙含量。成膜过程中，与非共混薄膜相比，完成共混薄膜所需的时间要少得多。合成了不同分子量的聚苯乙烯颗粒，并比较了由这些胶乳制成的薄膜的拉伸强度。发现抗张强度随分子量增加直至达到最大值，然后变得与分子量无关。分子量（重均分子量）而不是粒度是决定薄膜机械强度的主要因素。交联胶乳与非交联胶乳颗粒混合在一起。当未交联的聚合物链的长度不足以使其自身在界面处充分缠结时，与未共混的未交联的乳胶薄膜相比，相应的共混薄膜在强度上有明显的提高。考察了由聚苯乙烯反应性胶乳共混物组成的薄膜中聚合物相互扩散与交联反应之间的竞争，其中反应性基团（羧酸和伯胺）被并入了单独的胶乳颗粒中。通过控制分子参数，我们能够将成膜过程设计为可进行反应控制，从而可以提高膜的相应机械性能，例如膜模量，拉伸强度和韧性。建立了基于理论并经实验数据验证的模型，该模型可以为膜界面增强以及在涂料工业中的潜在应用提供有用的指导。

著录项

  • 作者

    Liu, Lili.;

  • 作者单位

    Lehigh University.;

  • 授予单位 Lehigh University.;
  • 学科 Chemistry Polymer.;Plastics Technology.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 247 p.
  • 总页数 247
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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