On the surface biodegradable plastics do not necessarily make a lot of sense. They are often more expensive than oil-based plastics, and may require industrial type composters to totally degrade.
They do make sense, however, for the American Nursery & Landscape Association, which has been studying ways to eliminate growing piles of waste from discarded plastic nursery pots.
Generally speaking, recycling isn’t a good solution for many reasons:
1) The economics of recycled plastics are weak because of highly cyclical resin prices.
2) Recycling rates are relatively low (25 percent at best) for the most recycled plastics-PET and HDPE. Nursery pots are made from a mishmash of plastics, but are mostly made from lightly recycled grades, such as polypropylene and polystyrene.
3) Nursery pot compounds are heavily loaded with fillers such as calcium carbonate to cut costs. Fillers impede recycling and are costly to remove.
4) Residual potting mix fouls granulators that shred plastic waste.
Increased re-use of pots is a possibility, but the industry needs to develop standards for pot sizes, finishes and materials. There are also sanitation issues.
So the ANLA and its research arm partnered with the U.S. Department of Agriculture to explore the potential to make biodegradable plastic from chicken feathers that are being landfilled. Tests are still under way to determine how well the bioplastic composts, and to what extent it requires blends of oil-based plastics to achieve required physical properties.
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