11 - Recycling of Plastics

Abstract

Plastic recycling is described as the process of recovering scrap or waste plastics and reprocessing the material into useful products, sometimes completely different in form from their original state. Classifying by the final product of any given recovery process recycling can be differentiated into three methodologies: pimary recycling, secondary recycling, and tertiary recycling. This chapter focuses on primary and secondary recycling where the plastic is reused rather than converted into chemicals or fuel to meet energy needs. There are several technologies to recycle plastics such as: single resins, mixed plastics, and compatibilization of plastic resins. There are numerous applications for recycled plastics. From reuse in the same application as initially used, whether at 100% or more commonly compounded at some lower quantity, to being used in less demanding applications, recycled plastics utilization has made dramatic in-roads in many industries. The manufacture of plastic lumber, however, exists almost solely because of recycling. The use of recycled alternatives to virgin plastic ensures that the product is more commercially competitive. Plastic lumber is typically made from recycled PE that may contain other plastics and/or fillers. Commingled plastics used with PE may include PVC, PS, PP, PET, and other materials. Fillers used in these systems may include glass fibers, PS fibers, or cellulosic fillers such as wood fibers. The principal use of plastic lumber is to replace wood in areas where weathering is an issue such as in decking, road barriers, or railroad ties.