Plastic is the world’s most popular packaging material thanks to its strength and durability but these are the very same reasons that make it difficult to break down if it accidentally ends up as litter in the environment. With an estimated 100 million tons of plastic floating in the ocean, killing an estimated 1 million sea birds and 100,000 sea mammals every year we think the ability to promote a faster break down is a pretty good thing!
And thanks to our Reverte technology we can make this happen. So lets have a close look at how Reverte works and the evidence that proves it accelerates the biodegradation of our packaging.
Plastic has a very high molecular weight that renders it too hydrophobic and, therefore, very resistant to microbial attack. Reverte is an additive masterbatch designed to be added to plastic in order to impart a controlled oxo-biodegradable characteristic. Oxo-biodegradability is a two stage process. The first stage is catalytic oxidative chain scission of the plastic causing a serial reduction in molecular weight which results in acute embrittlement and microfragmentation. The second stage takes place when the molecular weight has been sufficiently reduced to render it available for microbial biodegradation which breaks down the degraded residues to carbon dioxide, water and biomass.
The biodegradation of abiotically-degraded polymer material has been studied in detail by many scientists and published in peer-reviewed papers, most recently at the Technical Research Institute of Sweden and the Swedish University of Agricultural Sciences. A report of the work was published in Vol 96 of the journal of Polymer Degradation & Stability (2011) at pages 919-928, which shows 91% biodegradation in a soil environment within 24 months. These scientific papers form the basis for Standards published by BSi (8472), ASTM D6954 (USA), and AFNOR Accord T51-808 (France) to measure oxo-biodegradability.
We’re often asked the question “But doesn’t it just break up into little pieces”. There is plenty of evidence to prove that oxo plastic is chemically changed (evidenced by a massive drop in Molecular Weight), and that biodegradation does occur (evidenced by conversation of carbon to CO2). Perhaps the most simple approach to answering this question is to ask anyone disputing the biodegradation of our packaging to show their evidence that following the fragmentation stage that the oxo plastic they are referring to is just smaller pieces of the same plastic. To do this they would need to show that the Molecular Weight had remained the same but we can prove beyond any doubt, it is significantly reduced.
A number of oxo-biodegradable test methods and standards have been developed to enable oxo-biodegradation to be quantified and ASTM D6954 is widely considered the most appropriate protocol as it has been in the public domain since 2004 and has set the standard for demonstrating, evaluating and quantifying oxo-biodegradability in polymeric products. ASTM D6954 has a set of testing criteria laid out in three tiers. Tier 1 measures the initial degradation through molecular weight reduction, Tier 2 measures the biodegradation of the preoxidised Tier 1 material through test methods such as ASTM D 5338 (aerobic biodegradation under controlled composting conditions) and Tier 3 measures toxicity (through the absence of proscribed heavy metals) and eco-toxicity through germination and growth tests.
Reverte has passed these tests, at independent world leading testing facilities, with outstanding results and has demonstrated beyond a doubt that it does enable a product to fully biodegrade much faster than it would without Reverte. To give you an example, under ASTM Tier 2 testing, a checkout bag achieved > 95% mineralisation in just under 10 weeks which demonstrates the plastic has actually biodegraded.
It is also worth noting that our testing processes are very conservative. We apply Arrhenius Principles to results obtained at 50ºC, transposing them into the real-time results that would be expected at 20oºC as higher temperatures have the effect of accelerating the breakdown. Also the UV exposure in the ageing cabinet is only approx 26 kLy compared to the levels of 160 kLy to 180 kLy experienced in Australia – meaning the test plastics would need 6 – 7 years in the ageing cabinet to replicate 1 year on the Australian coastline.