Why is Recycling of Postconsumer Plastics so Challenging?

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.