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DuPont says its new series of Entira™ EP technology and copolymers are able to boost the performance of recycled polyolefins to a similar level as virgin resins, thereby improving the prospects for recycling mixed-plastics waste streams. 

Mixed waste streams containing polypropylene (PP) and polyethylene (PE) can be difficult to separate due to the similarities in densities. If one of these polymers contaminates the waste stream of the other, it tends to yield materials with very low mechanical properties. This can make it difficult or impossible to process such feedstock using standard polymer extrusion or injection technologies

DuPont’s Entira EP compatibilizers are based on ethylene copolymers. Adding them (typically 3-7 wt%) bridges the PE contaminant to the PP matrix (or vice versa), creating a homogeneous recycled resin. This leads to increased performance and surface properties for items manufactured with such “upgraded” recycled resins. The company claims that, in addition to being used to produce bulky items such as flower pots and outdoor furniture, the resulting recycled resins also are suitable for use in higher-value applications, as in thin films and membranes for the construction industry. 

“Incompatible plastics mixtures are very common in waste streams,” noted Loic Rolland, R&D Fellow, and Lucie Charbonnel, a marketing specialist with DuPont Performance Materials. “As a consequence, it is expensive and often nonprofitable for recyclers to collect, clean, sort, grind and melt process the streams. Our Entira EP technology can help solve this challenge, enabling recyclers to use less expensive plastic waste feedstock while producing recycled pellets with good properties, and to reach profitability in return.” 

DuPont said recyclers such as at Regeplastic in France are already successfully applying this technology. www.dupont.com