Biodegradable Polymers

[Jack Shapiro <>]

In support of Terry Pacey¹s message regarding plastic bags, I¹d like to add a few notes from my own experience in the polymer field. 

First, the use of biodegradable films is not recent or new and was commercialised from research findings into polymers interacting with light energy at the University of Toronto about 20 years ago.  A Canadian company that arose from this work offered a range of biodegradable films for growing fast growing crops, like strawberries.  These films were copolymers , consisting of chains of predominantly one type of repeating unit- ethylene, but with an occasional different ones - carbon monoxide.  The films were fabricated together with carbon black to absorb sun light.  The carbon monoxide incorporated into the polymer chair absorbs light energy from sunlight and starts a chain reaction, which leads to the disintegration of the film in a matter of months.  Such films are useful to lie over thawing out fields, keeping the soil warm, suppressing weed growth, and after harvesting the films are simply ploughed into the ground.  An alternative approach has been to mix substances, which absorb light, together with the polymer during its fabrication into films.

Similar approaches have been made to make other plastics degradable, leading to degradable, disposable coffee cups, and plastic planting pots.  These cases the plastic, polystyrene, is fabricated together with some biodegradable material like starch, or even tapioca, (as mentioned in one of Terry¹s references) which can be attacked, this time with bacteria to degrade the item in a short time.

Originally the biodegradable films and moulded objects looked like facing a bright future, but it seems that their cost has stopped them from wide use.  I am not sure whether these are still used extensively. 

Perhaps the time has now come to re-consider these types of products.  The Chinese Company, listed among Terry¹s references is now marketing products, which must be based on these principles for making biodegradable polymers.   

Below are appended two additional references collected from the internet.

Why not Australian companies?

Jack Shapiro

www.moea.state.mn.us/berc/dfe/polyvend.pdf 

http://pep.sric.sri.com/Public/Reports/Phase_2000/RP115D/RP115D.html