Tips From The Expert: Degradable Plastics – Are we there yet?

by Christine Wied

You may be seeing plastic items that claim that they are degradable but are they really and are they recyclable too? The Association of Postconsumer Plastic Recyclers that works with manufacturers that use postconsumer plastic as feed stock, despite study of the issue still has some doubts about the proven effectiveness of these products.

There are two types of materials involved in the issue. One set of plastics are made from Polylactic Acid (PLA). These are plant-based materials such as corn starch, potato starch, sugarcane and certain grasses. The idea of renewable sounds great but what about the ethical issue of using some of these food crops for plastics? Also, not all PLA plastics claim they will degrade.

The other degradable plastic is the standard #1 PET (water and soda bottles) or #2 HDPE (milk jugs) plastics with special additives that are supposed to aid in their breaking down. Normally plastic just breaks up into tiny pieces and doesn’t biodegrade. One big question is whether these two types of degradable plastics can be recycled with regular, petroleum-based plastics without the additives?  So far the answer seems to be NO.  These products are actually seen as contaminants in the plastics recycling stream. There does not seem to be sufficient infrastructure to capture and recycle them separately.

If they can’t be recycled, do these degradable bottles break down in a landfill at least? Again the research seems to indicate probably not. Most things do not break down in a modern landfill anyway but even with the additives, theses plastics would need the high heat in a commercial composting operation in order for the process to work. They will not breakdown in a backyard compost bin. Some commercial composters have taken certified degradable “greenware” only to find that little or nothing happened to it in a reasonable, expected amount of time like other organic materials such as yard waste and food waste.  If the compost is to be used in certified organic farming, these degradable plastics are not to be used as a component according to organic regulations.

Mixing recycled plastics with the degradable additives with standard plastics have some manufacturers concerned about the quality of their end products. Can they guarantee they will hold up with the same integrity and strength? What if the bales of plastics have been sitting out in the sun and weather waiting to be recycled?  When do the degradable components start to work? With some items it may not be a problem but what if the plastic is used to make strapping that holds a pallet of bricks on the back of a truck? The intent of these products is admirable but until more studies and improvements are made to ensure they work as claimed or have the right infrastructure to handle them separately, degradable plastics should probably be avoided.

Open Line Article, 4/25/2012

Contact: Christine Wied,

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