Is PLA Compostable?

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Polylactic acid or PLA is a material which has been around for tens of years. Until recently no major producer of PLA existed until they were funded by mega corporations to come into the marketplace to replace synthetic plastic. BioSphere Plastic has been asked is PLA biodegradable, while the answer is not simple we have decided to make a post to explain what PLA really does and some further reading for the inquiring minds.

1) PLA is not biodegradable, it is degradable.
2)Enzymes which hydrolyze PLA are not available in the environment except on very rare occasions.
3) Proteinase K catalyze the hydrolytic degradation of PLA

Williams in 1981 and Tsuji and Miyauchi in 2001 had the same question ” is PLA is biodegradable” . They have written white papers around the subject and are featured in the book Biomaterials Science: An Introduction to Materials in Medicine. In the book and discussed at the conference of the European Society for Biomaterials PLA is controlled by hydrolysis and the hydrolysis is independent of all biological agents.

So while many people believe PLA to be biodegradable, it simply is not, PLA is degradable and should be considered as such, in the Biomaterials Science book, they actually go on to say that the situation where Proteinase K hydrolyze PLA is so rare it is not worth discussing further.

We hope this answers the question on if PLA is biodegradable and we continue to work for the best solution for your green plastic and biodegradable needs here at BioSphere.

For more information regarding the documents listed in this article please visit.

Hideto Tsuji * and Shinya Miyauchi
Department of Ecological Engineering, Faculty of Engineering, Toyohashi University of Technology, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
Biomacromolecules, 2001, 2 (2), pp 597–604
DOI: 10.1021/bm010048k
Publication Date (Web): April 24, 2001
Copyright © 2001 American Chemical Society

Williams 1981
Engineering in Medicine January 1981 vol. 10 no. 1 5-7

Biomaterials Science: An Introduction to Materials in Medicine 2013
Buddy D. Ratner, Allan S. Hoffman, Frederick J. Schoen, Jack E. Lemons

Update 10/15/2018

As many people have read our website over the past few years we have shown that PLA does not biodegrade very fast or at all in most environments. We would like to share a recent study that was conducted by (Muniyasamy 2011) proving that in soil Polylactic Acid does very little if anything. PLA requires moisture and heat over 140F to begin the self hydrolyzation process reducing the molecular weight of the polymer to lactic acid. Polylactic Acid does not and will not biodegrade without these environments, if you have a home compost pile and it does not reach 140F and lacks water PLA will do nothing. It is important to understand PLA is not a biodegradable material in just any environment, it is a compostable material only in industrial environments and shows very little mineralization(not biodegradation) in the majority of environments. The biodegradation of PLA is reliant on Proteinase K as shown in our earlier post.

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 feed-stock to produce disposable items. According to Sudhakar Muniyasamy PLA virgin undergoes very little to no biodegradation of PLA virgin resin. PLA requires a lower crystalline material and by adding a blend of material for it to somewhat mineralize(not biodegrade) in soil environments. Moreover, this study shows limited results even at elevated temperatures of 20-30% mineralization of the material mixed with various other biopolymers. This proves what we have stated for years at BioSphere Plastic, Polylactic Acid does not biodegrade in a normal environment, it therefore should not be considered a biodegradable material as it is limited in what it can achieve and in what environments. Contact BioSphere Plastic LLC for further information on how to make your plastic biodegrade in all disposal methods.

You can view the soil degradation/mineralization of polylactic acid and blended polylactic acid below:

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