Wednesday, March 05, 2008
Degradable plasticI recently bought some apples and spotted an intriguing little logo on the back of the plastic packaging. I look carefully at just about all plastic packaging these days in an attempt to identify what type of plastic it is (and therefore how recyclable).
What I found was a bit different to what I was expecting. Below a little logo was a website reference, www.degradable.net. So, off to the website to find out what this was all about.
It turns out that these smart guys have developed a low cost additive for polyethylene and polypropylene which causes the plastic to break down into a biodegradable form (the long plastic chains break down into shorter chains which can then be accessed by micro organisms which break them down to carbon dioxide and water. You can read the full details on their site). Astrapak are the South African suppliers of these plastics. There are also some alternatives to the d2w process which make use of light sensitive, or starch additives.
The great benefit of this is that plastics which are disposed degrade much faster (they can be set to degrade after 60 days or up to 6 years later). One of the issues that this technique creates is that it impacts on recycling. The degradable plastic can be recycled, but in their words, "..there are many different and complex permutations of both input feedstock and output materials which need to be individually considered," i.e. it's complicated. It seems like it is easier to create recycled material that is degradable, while creating non–degradable recycled products is trickier.
This seems like a big disadvantage, but according to the EIA only 5% of plastics produced in America are recycled (I am sure that figure is much lower for South Africa). That means that up to 95% of the plastic produced ends up in land fills, water ways and generally strewn around the country side. At least using degradable plastics means that they will have a smaller, and shorter impact on our environment.
I am sure that a lot of people would rather argue the case for bioplastics. Personally I have always been sceptical of the benefits of bioplastics (and biofuels), mainly due to the pressure they place on food prices. More recently there have been some studies revealing that biofuels may damage the environment more  than emissions due to conventional fuels (bioplastics come from the same process, and therefore have a similar impact). So bioplastics may not currently have all the benefits that they claim.
Degradable plastic is a great product due to its reduced impact on the environment, but we do need to examine how we use and dispose of plastics. The reality is that plastic feedstock (oil) is a limited resource  and we need to use it wisely. Biofuels and bioplastics may not be the panacea that many people have hoped for. Only a small percentage of plastics are recycled. Plastics that are recycled are typically used to make other products rather than replace the recycled product, which means virgin feedstock is constantly required.
The real long terms solution is to reduce the amount of plastic we use, as well as reuse it as much as possible, and to continue recycling when a product reaches the end of its lifetime. So, in my mind, the question is this: how do we create plastic products with longer lifetimes? That is what really needs to change.
 "Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land Use Change" by Timothy Searchinger, et al.
 More on the negative impacts of biofuels.
 According to Waste Watch,
"It is estimated that 4% of the world's annual oil production is used as a feedstock for plastics production and an additional 3-4% during manufacture."
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About Engineer Simplicity
Engineer Simplicity specialises in the design and development of electronic products.
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