The truth about PLA

September 22, 2018

A few weeks ago I met up with an old workmate for drinks and a bit of a catchup, I was keen to check out a new spot by the river and grab a bite to eat where I was excited to find they made falafel wraps and they served their beer in “bio-cups”.

The cups proudly read, “I am not a plastic cup”, and “this cup is 100% Compostable & 100% Biodegradable”.  Hmmm, I thought, that’s a bold claim to make.

What is PLA?

The cup was made from Polylactic Acid (PLA), the wonder material made from waste plant-starch that is fully compostable and fully biodegradable. 

A simplified over view of the process is as follows - waste vegetable matter is fermented to produce lactic acid, following a few different reactions these small lactic acid monomers are polymerised to form the plastic PLA.

The whole process is less wasteful and polluting than traditional oil based approaches and doesn’t rely on a finite resource. Corn crops can be produced sustainably.

However, any material that claims to have the durability, uniformity, colourlessness and flexibility of plastic but can be chucked in your compost bin with your banana skins and to become worm-food, warrants closer inspection.

Is PLA biodegradable?

The truth is PLA could take 100s of years to biodegrade in a landfill, and chances are that is where this plastic-none-plastic cup will end up. To biodegrade over a short time-frame, PLA needs a source of oxygen (not typically present under vast piles of rubbish in a landfill), temperatures of 140ºC and above (somewhat hotter than the heat wave we’ve experienced this summer), and additional chemical additives. These conditions are only present at industrial composting sites and are hugely energy intensive.

These processes are highly complex and wasteful at every stage of the product lifecycle. Much like high-quality plastic, transparency in its production is vital.

Can PLA be recycled?

Another issue behind the use of PLA as a single-use plastic is encountered when it comes to recycling. PLA is often mixed in with PET (one of the most common household plastics recycled) recycling, the two are difficult to distinguish and as a result, PLA can contaminate PET being recycled resulting in lower quality recycling and a lower value end product.

Clearly then there are issues with this wonder polymer and its widespread implementation that are nowhere to be seen alongside claims of 100% biodegradability and compostability. I’d invite PLA producing companies to change their approach, consumers of eco-friendly products are savvy, not only that, but often this approach undermines their efforts and the efforts of others in this space. While there are strong benefits to the use of PLA these certainly aren't in it not being plastic, and definitely not it being compostable at home.

The advent of bioplastics is still in its infancy and there are many kinks that still need to be ironed out before we see widespread implementation, my worry is through being premature in the release of PLA products on the back of buzzwords and trends these companies may actually be doing more harm than good.

My best advice is to do your own research before believing everything you see and hear regarding bioplastics and similar changes in the industry. If you’re still stumped ask someone with some plastics knowledge, maybe a scientist, like me! 

I can be reached any time over on our instagram or facebook with any plastic related queries (or anything at all really), best of luck with your journey in reducing your plastic consumption.





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