PLA is a bio-based plastic derived from renewable resources, in this and most other cases corn starch. Therefore PLA is often referred to as corn starch plastic.
There are several advantages of PLA:
- PLA is made from corn starch, which is a renewable resource.
- PLA doesn't contain toxins.
- Producing PLA makes less greenhouse gas emissions, compared to standard plastics.
- The Step One bag is certified compostable according to AS4736.
- Less energy is needed in order to produce PLA, compared to producing standard plastics.
PBAT is petroleum-based and can therefore not be classified as made from renewable sources.
That said PBAT is actually enhancing the composting process and leaves no toxins when composted.
PBAT is known for its flexibility and toughness. This makes it perfect for combination with other biodegradable plastics that have high strength, but are very brittle (like corn starch plastic). This combination is a great way to replace standard plastics with an environmentally safe and biodegradable alternative, that will harmlessly degrade in a short time.
The reason for using PBAT combined with PLA, is that it preserves and enhances the biodegradability of the PLA and adds flexibility and strength similar to standard plastics.
Sources and useful links:
PLA:
- https://en.wikipedia.org/wiki/Polylactic_acid
- http://www.bionomicfuel.com/corn-starch-plastic-the-advantages-and-disadvantages/
PBAT:
- https://en.wikipedia.org/wiki/Polybutylene_adipate_terephthalate
- https://www.betterpackaging.com/what-is-pbat/
AS4736 Standard:
- https://www.bioplastics.org.au/resources/faq/