From films and fibers to car components and household products: recycled polypropylene (R-PP) has a wide range of applications. This broad portfolio of applications is possible thanks to different molecular structures and variable degrees of crystallinity of various PP types.
Currently, PP regrinds and PP regranulates are mostly available as non-food grade recyclates. This situation is associated with challenges regarding the separation of food-grade and non-food-grade PP waste material during collection and sorting. However, the introduction of special technologies like markers for the separation of plastic waste is expected to change this.
PP regranulates are suitable both for injection molding as well as a wide range of extrusion applications. In order to produce high-quality products and fulfill the application-specific demands, commonly, the recycled PP is mixed up to 50% with a virgin PP.
A wide range of products for various outdoor or indoor application fields can be manufactured using the recycled PP: edging, composite lumber, plant pots, furniture for garden, industrial fibers, pipes, pallets, crates, automotive parts, speed humps, playground equipment, paint cans, transport boxes to household goods, dishware, buckets and pails, compost bins, food containers, cover caps and closures, home storage, sporting goods, battery cases or clothing fibers. Thanks to continuous improvement of the recyclates’ quality, this list is continuously being extended.
Polypropylene (PP) is a versatile thermoplastic polymer that belongs to the polyolefin group. Similar to virgin plastic, recycled PP has valuable material properties, like high flexural and impact strength, good fatigue resistance, and high chemical resistance against most organic solvents, many acids, and bases at room temperature. The density of neat PP recyclates (without filler or reinforcement) lies in the range of 0.90 to 0.92 g/cm³ and is comparable to that of a virgin PP.
There are various feedstock sources for recycled PP including different applications and products. Consequently, the individual material properties of a given recyclate strongly depend on the source. For example, the post-consumer PP regrind and flakes are often multicolored and the corresponding regranulates are usually black or gray.
The recycled post-industrial PP is available as a translucent plastic, in white or further colors. In order to fulfill application-specific requirements, the material properties of a recycled PP can be improved by mixing with a virgin PP or use of additives like fillers or reinforcing materials, stabilizers, color masterbatch, etc.
PP is the most commonly used polymer after polyethylene (PE). The main feedstock source for PP recyclates is food and non-food packaging. Post-consumer PP raw material is typically retrieved from drinking bottles, bottle caps, food trays, pans as well as various containers.
The sources for post-industrial PP are more versatile and include various components from injection molding and extrusion (including films and sheets) as well as fiber production. The principal steps of collection, sorting, and extrusion of post-consumer and post-industrial PP waste materials undergo a continuous improvement process to ensure and improve the quality of the recyclates.