Once an admirable goal for plastic packaging and single-use plastic products, recycling of late has been called “garbage” (New York Times Magazine), “greenwashing” (Greenbiz) and “The Great Recycling Con” (New York Times). In the latter article, authors Tala Schlossebers and Nayeema Raza call recycling “propaganda” because the industry “wants to trick us into thinking we can use as much plastic as we want so long as we recycle.”
Gee, Tala and Nayeema, tell us how you really feel about recycling!
Recycling seems to have hit a brick wall primarily because of problems associated with the incompatibility of various plastics. “Current plastic recycling and sustainability goals are limited by the intrinsic incompatibility of many polymers and the negative effect of fillers and impurities on end-product properties, thus requiring a high degree of expensive sorting, separating and cleaning,” Sal Monte, President of Kenrich Petrochemicals Inc. (Bayonne, NJ), told PlasticsToday. Another barrier is that the melt processing of polymers causes “chain scissoring,” resulting in recycle and regrind materials having inferior properties compared with virgin resins.
That is why sorting—a labor-intensive activity that results in a lot of waste—is necessary. Monte noted that the reason for separating #1 (PET) and #2 (HDPE) from #5 and #7 is because of the incompatibility between the materials, “unless you use titanium/aluminum additives that perform in situ catalysis of polymers and coupling of fillers,” he said. Using innovative additive technology that permits co-mingling of plastic materials into a single waste stream and deriving value from these materials to produce new products is the Holy Grail of recycling.
Monte said that current compatibilizers offered to recyclers are based on co-polymers or maleic anhydride (MAH) modified polymers. “Co-polymer compatibilizers require extensive sorting to match up the polarities of the recycled materials, and maleic anhydride often depolymerizes condensation polymers such as PET and nylon, obviating their use in post-consumer recycle,” explained Monte. “MAH technology claims to be a coupling agent, which is true for rebuilding polymer molecular weight, but it’s a misnomer when applied to coupling filler and organic interfaces.”