Post-consumer PVC recycling is a crucial aspect of sustainability in plastic pipe production. Unlike some other plastics that may degrade or lose stabilizers quickly, PVC is inherently stable and can undergo several rounds of recycling without significant degradation. This stability contributes to its potential for long lifetimes, estimated in the hundreds of years.
Recycled PVC material is frequently incorporated into the core of multi-layer pipes, such as foam core pipes. This application is considered a "safe place" for lower-grade recycled material because the core structure in a sandwich pipe carries only a fraction of the load compared to the skins.
Successful use of post-consumer recycled PVC in pipe extrusion requires attention to several factors. The material typically needs to be pulverized to a specific particle size. For example, pulverizing to approx. 750 micron costs Euro 40,-/ton, while a finer 500 micron size costs about Euro 80,-/ton.
Failure to manage these aspects can lead to high wear on screws and barrels (S&B wear) and issues with material consistency. For larger pipes with thicker skins, slightly coarser micronizing might be acceptable as foreign particles like sand or rubber are less likely to protrude through the skins.
Higher levels of CaCO₃ can be added to the core formulation along with recycled PVC to achieve required stiffness while potentially reducing total wall thickness. This combination can also allow for more blowing agent addition without blistering, enhancing cost savings.
Regional regulations and initiatives, such as those promoted by organizations like TEPPFA (Europe), SAPPMA (South Africa), PVC4pipes, and Uni-Bell (USA), influence the adoption and practices of PVC recycling in pipe applications.