When someone says to you that their polyethylene bags, etc are bio based and better for the environment, you need to know right now that the plastic produced is no different to petrochemical based polyethylene. What is different is the original age of the substances used to produce them and that bio based polyethylene is generally made from alcohol derived from the fermenting of sugar cane, sugar beet, corn, wheat and other grain etc and that as long as we grow these crops the source of the plastic can be “renewed” many many times. It’s only renewable in the sense that it can be grown over and over and green in the sense that it is grown and takes in some carbon dioxide in the process of growing but it will contribute to many more plastics that will ultimately end up in the ocean, as landfill or breaking down into Microplastics. So don’t be fooled by this clever marketing when going plastic free.
Here’s a little basic chemistry lesson about Polyethylene to help you out.
“Poly” means many.
“Ethylene” is a gaseous material also sometimes called Ethene. It’s name comes from from the word ether (Ethyl alcohol) plus “yl” which means building stuff or raw material and “ene” which has no meaning in itself but is used in chemistry terminology as a name forming element.
Ethylene occurs naturally on a very small scale in plants to help fruits ripen and flowers bloom (sounds fairly harmless doesn’t it and at the small scale in plants it is). However when created in the laboratory or refinery it is highly flammable and poisonous. Chemists tell us it is a very basic substance consisting of two carbon and four hydrogen molecules.
Polyethylene basically means “many ethylene”
While ethylene occurs naturally in plants as explained above, it can also be created in a refinery via process called “steam cracking” which involves subjecting the chosen starting materials (usually petroleum by products) to extreme temperatures (750-950C) and then some further refining using distillation and condensation.
Most ethylene is converted into polymers (Poly again meaning many and mers meaning parts) which serve as building blocks for plastic. Ethylene polymers are long chains of ethylene that can be manipulated into all kinds of shapes. They then may be transformed into plastic bags, films, packaging, bin liners (trash for you American folks) or used to make food storage containers and other household objects. Ethylene gas is also used in styrene production, which can then be used to make synthetic rubber tires or even foam building insulation but we will cover that in another article.
The basic building block of polyethylene is ethylene. Ethylene is chemically similar to, and can be derived from ethanol which can be produced by fermentation of agricultural items such as sugar cane, sugar beet, wheat grain or corn.
This is where the renewable or green labelling comes from as you can grow plants and foodstuffs to turn into ethanol, then ethylene and then plastic.
Bio-derived polyethylene is chemically and physically identical to traditional polyethylene – it does not biodegrade.
The Brazilian chemicals group Braskem claims that using its method of producing polyethylene from sugar cane ethanol captures (removes from the environment) 2.15 tonnes of per tonne of Green Polyethylene produced. However it is still the same final product as the petrochemical based polyethylene and still creates the same problematic waste. Per Braskem’s own literature the only way to tell the difference between their sugar cane based polyethylene and a traditional petroleum based polyethylene is by doing Carbon14 testing which will show that the molecules are younger.
Rather than encourage crops to be grown solely to make more polyethylene bags etc look to using cloth or string bags and share this article with others so they are not fooled either. Encourage people to get educated and go plastic free. There are quite a few available online. I chose these ones as they not only are plastic free bags, but also have a stainless steel closing clasp and the company promises plastic free shipping which I have not seen with other affiliates yet.
You can find some completely plastic free reusable bags like the ones pictured above by clicking on the link here: Plastic Free Shopping Bags
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