There are a lot of new buzzwords being thrown around related to “organic” plastics such as Bio-based plastics, Oxo-degradable plastics, Bioplastic and Compostable plastic. There’s a fundamental difference between all of these, so let’s dive in!
What is Bioplastic?
Bioplastics are regular plastics made from renewable sources such as cellulose or starch. Bioplastic is misleading because it suggests that any polymer derived from the biomass is environmentally friendly. They are NOT biodegradable in normal conditions! They need to be in industrial composting for a few weeks to decompose. This however, is still a better alternative to Petrochemical plastic that comes from fossil fuels (regular plastic). The use of the term “bioplastic” is discouraged. Use the expression “biobased polymer” instead.
The most common bioplastic you’ll see today is “PLA” or Polylactic Acid. All the bags you see that say ” I AM NOT PLASTIC” are made of this. Polylactic acid is a thermoplastic aliphatic polyester derived from renewable biomass, typically from fermented plant starch such as corn, cassava, sugarcane or sugar beet pulp. PLA is one such example that can only biodegrade in industrial conditions*. PLA only offers two benefits over regular plastic, a) that it’s not made from fossil fuels b) Regular plastic loses value as soon as it melts, PLA can be melted and reused easily.
It is important for government bodies worldwide that are considering using PLA to understand that, unless you have a controlled industrial compost facility this polymer will do very little if anything. You will have the same or similar problems of regular plastics except you are now using feedstock to produce disposable items.
*PLA requires moisture and heat over 140F to begin the self hydrolyzation process reducing the molecular weight of the polymer to lactic acid. Only shows very little mineralization in the majority of environments. PLA required Proteinase K to break down, which is very hard to find in the natural environment and expensive to manufacture.
What is Bio-based Plastic?
Bio-based are some conventional plastics such as PP, PET etc. blended usually with starch to obtain biological decomposition of plastic product into smaller pieces. STILL BAD!
What is Compostable Plastic?
‘Compostable’ suggests that you can throw this plastic into your home compost (Daily Dump can help you start!). These plastics degrade quite quickly often in around 35 days. However, in order for this to be true, you have to look for the words ‘home compostable’. In reality just the word ‘compostable’ often entails that the plastic is made of PLA and can only be composted in industrial composting facilities. If you throw the plastic on your home compost pile it most likely won’t degrade because the temperatures are often too low.
What is are Oxo-degradable Plastics?
Oxo-degradable plastics are fully made of conventional plastic with the addition of special plasticiser that degrades after some time (doesn’t matter in which environment). Again, they are conventional plastic materials with artificial additives that do not biodegrade but merely fragment into small pieces that remain in and potentially harm the environment and endanger recycling and composting because you can’t tell them apart from normal plastic. As of 2018, Oxo-degradable plastic has been banned in the EU.