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首页> 外文会议>Silicones and silicone-modified materials symposium >Chapter 13 The Gel Point and Network Formation Including Poly (dimethylsiloxane) Polymerizations: Theory and Experiment
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Chapter 13 The Gel Point and Network Formation Including Poly (dimethylsiloxane) Polymerizations: Theory and Experiment

机译：第十三章包括聚二甲基硅氧烷聚合在内的胶凝点和网络形成：理论与实验

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Gel points, accounting for intramolecular reaction, are predicted using Ahmed-Rolfes-Stepto (ARS) theory. They are compared with experimental gel points for polyester (PES)-forming, polyurethane (PU)-forming and poly(dimethyl siloxane) (PDMS) polymerisations. The PES and PU polymerisations were from stoichiometric reaction mixtures at different initial dilutions and the PDMS ones were from critical-ratio experiments at different fixed dilutions of one reactant. The ARS predictions use realistic chain statistics to define intramolecular reaction probabilities and employ no arbitrary parameters. Universal plots of excess reaction at gelation versus ring-forming parameter are devised to enable the experimental data and theoretical predictions to be compared critically. Significant deviations between experiment and theory are found for the PU systems and the PDMS systems with higher molar-mass reactants. However, ARS theory fits well the results for the PES systems and the PDMS systems having lower molar-mass reactants. Possible reasons for these differences in behaviour are discussed in terms of the PU-forming reaction mechanism and the effects of entanglements in PDMS. Whilst ARS theory provides a good basis for gel-point predictions and can be applied to many types of polymerisation, more experimental systems at different initial dilutions and ratios of reactants still need to be studied and the various methods used for detecting gel points still need to be compared to enable a definitive assessment of its performance to be made.
机译：使用Ahmed-Rolfes-Stepto（ARS）理论预测分子内反应的凝胶点。将它们与形成聚酯（PES），形成聚氨酯（PU）和聚（二甲基硅氧烷）（PDMS）聚合的实验胶凝点进行比较。 PES和PU聚合来自不同初始稀释度的化学计量反应混合物，而PDMS聚合来自一种反应物不同固定稀释度的临界比实验。 ARS预测使用现实的链统计来定义分子内反应的概率，并且不使用任何参数。设计了凝胶化时过量反应相对于成环参数的通用图，可以对实验数据和理论预测进行严格比较。对于具有更高摩尔质量反应物的PU系统和PDMS系统，发现实验与理论之间存在重大偏差。但是，ARS理论非常适合具有较低摩尔质量反应物的PES系统和PDMS系统的结果。根据PU形成反应机理和PDMS中纠缠的影响，讨论了这些行为差异的可能原因。尽管ARS理论为凝胶点预测提供了良好的基础，并且可以应用于多种类型的聚合反应，但仍需要研究更多在不同初始稀释度和反应物比例下的实验系统，并且仍然需要研究用于检测凝胶点的各种方法。进行比较，以便对其性能进行确定的评估。

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