Biopolymers in the Existing Postconsumer Plastics Recycling Stream
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The existing plastic bottle reclaiming industry has working technology, satisfied customers, raw material, and investors. Adding new materials to the current mix requires satisfying all four needs for those materials. Rigid plastic container recycling focuses on high-density polyethylene (HDPE) and polyethylene terephthalate (PET) bottles, the overwhelming percentage of bottles sold in North America. Bottles of other resins, including polyvinyl chloride (PVC), polypropylene and biopolymers, lack critical mass necessary for independent reclamation. To be mechanically recycled, biopolymers must be either completely fungible with existing recycled resins or be available in sufficient quantity to achieve the needed critical mass. So far, biopolymer volume projections are not encouraging. Biopolymers, like all minor bottle resins, must pay their own way in sorting and processing without subsidy from PET and HDPE recycling. Based on limited data, some biopolymers may have little effect on recycled HDPE performance, but will represent a yields loss and added economic burden at some level of occurrence. Biopolymers have not been shown to be compatible with PET and likely will represent performance problems and economic burdens at even low levels of occurrence. Applications for biopolymers should be carefully selected so as to not interfere with currently recycled materials unless critical mass can be achieved quickly.