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Hello greenplastisnet,

I know that burning plastic has some very bad outcomes and should be avoided.  I was wondering if there has been any study on what happens to the bioplastics (any of them) when they are burned.  Do they still release harmful chemicals?  If they are burned will it speed up the process of them degrading?  I am looking to design a product that will be an ecological upgrade to a current widely used item, and this product will more than likely be burned.  Thank you for any information that you do have and if not could you maybe point me to someone that I could talk to about this.
Nate

RESPONSE FROM GREEN-PLASTICS.NET:

This is a very good question, and I'm glad that you asked.

The harmful results of incinerating, or burning, plastics are mainly associated with the release into the atmosphere of dioxins and heavy metals. Dioxins are chlorine-containing organic molecules, and are very toxic.  Some polymers inherently give off chlorine when they are burnt; for example, polyvinylchloride (PVC) is especially harmful because of the high levels of dioxins released into the atmosphere.  Other plastics, like polypropylene, give off only water vapor and carbon dioxide, and so are not inherently toxic when they are burned.  However, plastics can also have additives that are toxic, such as heavy-metals. These will be released as poison into the atmosphere when the plastic is burned, even if the polymer itself does not produce dioxins.  This is the reason that commercial incinerators have such strict guidelines regulating the way that they handle the disposal of plastics.

So what about bioplastics?  True bioplastics—biodegradabe plastics made from renewable resources, such as PLA—generally contain only carbon, oxygen, and hydrogen atoms, and specifically do not contain chlorine atoms. Because they do not contain chlorine atoms, they do not produce dioxins during burning/incineration. Traditionally, bioplastics also do not have heavy-metal additives. So in general they can be safely incinerated, with no danger of releasing dioxins or heavy metals.

However, it is still important to consider the details of the particular plastic you are working with. If a plastic is made from traditional (petroleum-based) polymers and has simply been made "degradable" through the inclusion of additives, it will still produce dioxins when it is incinerated.  If a plastic that is made from renewable plant materials has been processed in a way that involves the addition of heavy metal additives, then it will release those toxins into the atmosphere when it is incinerated.  These are the questions you will have to ask when considering how to dispose of whatever type of bioplastic material you work with.

Good luck with you project!