Tsampanakis Ioannis, Orbaek White Alvin
Energy Safety Research Institute, Swansea University, Bay Campus, Swansea SA1 8EN, UK.
Chemical Engineering, Faculty of Science and Engineering, Swansea University, Bay Campus, Swansea SA1 8EN, UK.
Polymers (Basel). 2021 Dec 29;14(1):112. doi: 10.3390/polym14010112.
The inherent value and use of hydrocarbons from waste plastics and solvents can be extended through open-loop chemical recycling, as this process converts plastic to a range of non-plastic materials. This process is enhanced by first creating plastic-solvent combinations from multiple sources, which then are streamlined through a single process stream. We report on the relevant mechanics for streamlining industrially relevant polymers such as polystyrene (PS), polypropylene (PP), high-density polyethylene (HDPE), and acrylonitrile butadiene styrene (ABS) into chemical slurries mixed with various organic solvents such as toluene, xylene, and cyclohexane. The miscibility of the polymer feedstock within the solvent was evaluated using the Relative Energy Difference method, and the dissolution process was evaluated using the "Molecular theories in a continuum framework" model. These models were used to design a batch process yielding 1 tonne/h slurry by setting appropriate assumptions including constant viscosity of solvents, disentanglement-controlled dissolution mechanism, and linear increase in the dissolved polymer's mass fraction over time. Solvent selection was found to be the most critical parameter for the dissolution process. The characteristics of the ideal solvent are high affinity to the desired polymer and low viscosity. This work serves as a universal technical guideline for the open-loop chemical recycling of plastics, avoiding the growth of waste plastic by utilising them as a carbon feedstock towards a circular economy framework.
废塑料和溶剂中的碳氢化合物的固有价值和用途可以通过开环化学回收得以扩展，因为这一过程能将塑料转化为一系列非塑料材料。通过首先从多种来源创建塑料 - 溶剂组合，然后通过单一工艺流程进行优化，可增强这一过程。我们报告了将工业上相关的聚合物，如聚苯乙烯（PS）、聚丙烯（PP）、高密度聚乙烯（HDPE）和丙烯腈丁二烯苯乙烯（ABS），简化为与甲苯、二甲苯和环己烷等各种有机溶剂混合的化学浆料的相关机理。使用相对能量差方法评估了聚合物原料在溶剂中的混溶性，并使用“连续介质框架中的分子理论”模型评估了溶解过程。这些模型用于设计一个间歇过程，通过设定适当的假设，包括溶剂的恒定粘度、解缠控制的溶解机制以及溶解聚合物的质量分数随时间线性增加，来生产每小时1吨的浆料。发现溶剂选择是溶解过程中最关键的参数。理想溶剂的特性是对所需聚合物具有高亲和力且粘度低。这项工作为塑料的开环化学回收提供了通用的技术指南，通过将废塑料用作碳原料，避免废塑料的增长，朝着循环经济框架发展。
