Recycled Polystyrene (R-PS)

Depending on the form of the virgin PS, various recycling approaches can be used for the recycling of PS. Recycled PS is mostly used as a non-food grade. Application-specific properties of PS can be optimized by mixing with virgin PS or using additives like color masterbatches, impact modifiers, etc. The recycled PS can be processed into PS pallets, which are then used for the storage and transport of goods, production of thermal insulation for window profiles, or fabrication of cost-effective extruded PS (XPS) insulation boards. Further applications of recycled PS include light switches, rulers, vents, shipping containers, carpet cassettes, clothes hangers, polystyrene furniture cores, and more.

The recycled EPS can be used for the manufacture of new polystyrene boxes, foam peanuts, packaging for electrical appliances or for snack bars, seating and insulation in cars, floor, wall, and flat roof insulation, and use in rafts and life jackets to create buoyancy. Furthermore, the recycled PS can be used for the manufacture of various composite materials or decoration elements.

There are claims about the development of food-grade PS recyclates using chemical recycling, but currently, these materials are not commercially available.

Properties of PS vary depending on its form and can be further optimized with regard to the desired application using various additives. Virgin PS is available in various forms: general-purpose PS (GPPS), which is translucent, stiff, and brittle, finds application in refrigerator trays, boxes, medium-impact PS (MIPS) in various injection molding applications, high-impact PS (HIPS) in electronic and applications, expanded PS (EPS, Styrofoam or polystyrene foam) in construction and packaging, and XPS in insulation.

All of these PS types are recyclable, although typically GPPS, MIPS, and HIPS waste fractions are mixed. The quality of the PS recyclates is strongly influenced by the contamination degree of the input stream and the used recycling technology. If the appropriate processing parameters are selected, the PS recyclates can be given properties similar to those of the virgin material. Due to its low bulk density as well as a high air and contamination content, the recycling of PS is associated with high logistic and pretreatment costs.

Post-consumer rigid polystyrene feedstock includes mostly various food-grade and non-food-grade packaging waste materials like coffee cup lids, meat and poultry trays, egg cartons, fish boxes, takeaway food containers, plastic cutlery, yogurt pots, CD and DVD cases, jewelry boxes, and further similar products. The EPS recyclates are generated by the various types of building and construction insulation.

The post-industrial PS feedstock covers PS waste materials diverted during the manufacturing process of PS-based articles. Typically, PS recyclates are available in various grades like a regrind, regranulate, or recompound.