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首页> 外文期刊>RSC Advances >Dissolution of epoxy thermosets via mild alcoholysis: the mechanism and kinetics study
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Dissolution of epoxy thermosets via mild alcoholysis: the mechanism and kinetics study

机译：通过轻度醇解溶解环氧热固性塑料的机理和动力学研究

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Thermoset dissolution based on degradable bond or exchange reaction has been recently utilized to achieve thermosetting polymer dissolution and recycling. In this paper, an industrial grade epoxy thermoset was utilized as a model system to demonstrate the thermoset dissolution via solvent assisted transesterification (or alcoholysis) with high efficiency under mild conditions. The anhydride–cured epoxy thermoset was depolymerized by selective ester bond cleavage in 1,5,7-triazabicyclo[4,4,0]dec-5-ene (TBD)–alcohol solution below 180 °C at ordinary pressure in less than two hours. The epoxy dissolution proceeded in a surface erosion mode via transesterification that was coupled with catalyst–alcohol diffusion. Based on this observation, a surface layer model containing three layers, namely the gel layer, solid swollen layer and pure polymer layer was used to analyze the thermoset dissolution kinetics. The epoxy dissolution kinetics was derived from the surface layer model, which could be used to predict the dissolution rate during the diffusion-rate-controlled dissolution process well. The results show that alcohols with larger diffusivity and better solubility lead to a higher alcohol/catalyst concentration in the gel layer and promote faster erosion and dissolution of epoxy. This is the first work to show that it is possible to depolymerize industrial epoxy using the principle of dynamic bonds with fast dissolution rate at mild temperature under ordinary pressure.
机译：最近已经利用基于可降解键或交换反应的热固性溶解来实现热固性聚合物的溶解和再循环。本文以工业级环氧热固性塑料为模型系统，通过温和条件下溶剂辅助酯交换（或醇解）的高效热固性溶解实验。酸酐固化的环氧热固性树脂通过选择性酯键裂解在低于180°C的1,5,7-三氮杂双环[4,4,0] dec-5-ene（TBD）-醇溶液中于常压下于不到两个压力下解聚小时。环氧乙烷溶解通过酯交换作用以表面腐蚀方式进行，并与催化剂-醇的扩散相结合。基于该观察结果，使用包含三层的表面层模型，即凝胶层，固体溶胀层和纯聚合物层来分析热固性溶解动力学。环氧溶解动力学源自表面层模型，可用于很好地预测扩散速率控制的溶解过程中的溶解速率。结果表明，具有更大扩散性和更好溶解性的醇导致凝胶层中更高的醇/催化剂浓度，并促进环氧树脂的更快腐蚀和溶解。这是首次证明可以在温和的温度和常压下使用动态键合原理以快速溶解速率解聚工业用环氧树脂。

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