The ubiquitous use of plastics has been driven by their combination of low cost and properties, but these attributes directly challenge waste management schemes for plastic recycling. Some postconsumer recycling programs are now nearly 50 years old, but a significant fraction of plastics still finds landfills or other dumping strategies at their end of life. With the growing concern regarding plastic waste, especially ocean plastics, there is a need for innovation and alternative strategies for the economic translation of plastic waste to valued product(s) that will promote their efficient circular utilization. This review first describes the technical and economic hurdles associated with the recycling of postconsumer plastics, but then it focuses on providing an overview of emergent strategies to recover plastic waste through new polymer design, new recycling processes, and chemical transformations to value-added products. Specific challenges discussed include plastic waste sorting and separations, product variability including additives, and the high efficiency/low cost in which the existing petrochemical industry can produce virgin polymers, in particular polyolefins. Although a wide variety of technical strategies have been demonstrated for recycling of plastics through both mechanical and chemical means, the commercial success of these different strategies is generally limited by either performance, including large variance in key metrics, or economics where the products can match the performance of virgin materials but the recycling process is expensive. Successful capture of postconsumer plastic waste through recycling likely will depend on economic incentives and government regulations.

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为什么消费后塑料的回收如此具有挑战性？

塑料的普遍使用是由其低成本和特性的结合推动的，但这些特性直接挑战了塑料回收的废物管理计划。一些消费后回收计划现在已有近 50 年的历史，但很大一部分塑料在使用寿命结束时仍会进行垃圾填埋或其他倾倒策略。随着对塑料垃圾，尤其是海洋塑料的日益关注，需要创新和替代战略，将塑料垃圾经济转化为有价值的产品，以促进其有效循环利用。本综述首先描述了与消费后塑料回收相关的技术和经济障碍，然后重点概述了通过新聚合物设计回收塑料废物的紧急策略，新的回收工艺，以及向增值产品的化学转化。讨论的具体挑战包括塑料废物分类和分离、包括添加剂在内的产品可变性，以及现有石化行业生产原生聚合物（尤其是聚烯烃）的高效率/低成本。尽管已经证明了通过机械和化学手段回收塑料的各种技术策略，但这些不同策略的商业成功通常受到性能的限制，包括关键指标的巨大差异，或者产品可以匹配的经济性原始材料的性能，但回收过程是昂贵的。