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Introduction

To tackle the pollution caused by non-degradable plastics made from fossil fuels, plastics made from renewable resources were developed and they have many benefits – reduced dependency for oil, reduced litter, compostable, etc. However, in comparison with the petroleum based plastics, they have a clear set of limitations – very costly, disrupt the existing recycling stream, poor technical performance, reduced shelf life (Many plastics products are exposed to extreme thermal, mechanical conditions). Bioplastics is always tagged with “Degradable but costly” in the market among the consumers.

Though the bioplastic industry leaders have made efforts to overcome some of these limitations, with innovations in technology and blending of resins, a new set of plastic products (Plastics with Additives) entered the market to co-exist with plastics and bioplastics and that claims to provide the answer for “Degradable and cheap” plastics.

What are these cheap alternatives for bioplastics? Are the promises made by these players true or they are a marketing gimmick? Can they stand up to scientific testing and standards? Do they classify as bioplastics?

This post analyses the science and technology behind these plastics with additives that degrade over a period of time and dissects the confusion prevailing over the claims made by these plastic manufacturers.

What are these plastics with additives?

Today, there exists two types of plastic products that contain additives to help them degrade over a period of time. They are oxo-degradable and enzyme-degradable plastics. These additives/enzymes are added to conventional polymers like (PET,PE,PP, etc) and once they are disposed off in a favourable environment, the plastic starts to degrade. Wonder how? Here we try to explain you about these wonders in simple terms.

How Oxo-degradable plastics work?

  • They are based on conventional plastics, like polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyethylene terephthalate (PET), to which additives, that should cause the plastic to degrade by a process initiated by oxygen and accelerated by light and/or heat, are added at the manufacture stage (Masterbatch Technology).
  • The additives are typically metal salts of carboxylic acids or dithiocarbamates based on cobalt (Co), iron (Fe), manganese (Mn) or nickel (Ni), with Co being used more for packaging and Fe and Ni more for mulch film. Other transition metals like Cerium (Ce) have also been reported to exhibit strong pro-oxidative effects.
  • Additive Producers – Add-X Biotech, EKMDevelopments, EPI, Wells Plastics Ltd, Willow Ridge Plastics Inc, d2w by Symphony International

How enzyme-degradable plastics work?

  • Similar to oxo-degradable plastics, conventional plastics (Enzyme will work on all polymers other than Nylon (6,6)) can also be enriched with organic additives, resulting in so called “enzyme-mediated degradable” plastics.
  • The degradation process is claimed not to be initiated by heat, UV light, mechanical stress or oxygen, but by the micro-organisms themselves.
  • According to the producers of “enzyme-mediated degradable” additives, the organic additive, together with its carrier material (in most cases this is ethylene vinyl acetate), is consumed by the micro-organisms, during which these excrete acids and enzymes that should break down the plastic into materials that are easily consumed by microbes.
  • Enzyme Producers – Earth Nurture (ENA® additive), ECM Bio-Films, Bio-Tec Environmental (Ecopure®), Enso Plastics

Key selling points for the plastics with additives

  • They are cheaper when compared to bioplastics alternatives
  • They will look andfeel like a conventional plastic and will not lose any of their original properties during their useful life.
  • If an oxo-biodegradable plastic bag or packaging film find its way into the environment, it will not lie around for decades causing a visual intrusion, blocking water courses and endangering wildlife
  • The time for degradation can be controlled, and the length of the service life can be decided by the commercial end-user
  • No genetically modified ingredient
  • They can be utilized in the conventional plastic manufacturing technologies.

Key market segments for oxo and enzyme degradable plastics

The key market segments and end use applciations of the oxo and enzyme degradable plastics include 

  • Flexible shopping bags
  • Semi-rigid plastic packaging for food, magazines and consumer-durables
  • Garbage bags and bin-liners for household use
  • Shrink wrap, pallet wrap and cling film
So what’s the confusion surrounding these “wonder plastics” if they are a cheap alternative to bioplastics to reduce plastic pollution?

Bioplastics Guide analyzes the reasons for the turmoil caused by these oxo and enzyme degradable plastics.

Reasons for turmoil in the market

  • The exact environment in which the oxo-biodegradable product may end up cannot be controlled, and so specific claims as to the time and extent of degradability cannot be justified.
  • Although evidence of the degradation of oxo-degradable plastics is easy to find, it is less clear to what extent the fragments of plastic are degradable (i.e. capable being broken down into carbon dioxide and water by the action of bacteria and fungi).
  • Another area of uncertainty is the fate of plastic fragments that remain in the soil after degradation of the oxo-degradable products. It is possible that the plastic fragments may become ingested by marine organisms, earthworms, insects, birds or animals.
  • The presence of oxo-degradable in the recycling stream may have an adverse effect on the quality and usability of the products made from the recycled material.
  • So far, no scientific evidence of complete biodegradability of enzyme-mediated plastics has been found. Not even the basic principle of enzyme-mediated degradation is scientifically explained in any publicly available documents.

Policies, Regulations and Bans surrounding these plastics with additives

In this section, we look at the markets that have either adopted or banned these plastics with additives and the policies and regulations for the same in the key market regions.

  • France – A group of members of the French National Assembly proposed a law to ban oxo-biodegradable plastics in 2014 – not on the basis that they pose risks to health and the environment, but on the basis that they just might. However, the bill was not passed by the government.
  • UAE – The government of UAE, in 2012, banned plastic products such as flexible shopping bags and semi-rigid plastic packaging for food, magazines, consumer-durables, garbage bags, bin-liners for household use, shrink wrap, pallet wrap and cling film and has made OXO biodegradable bags compulsory to all the stakeholders. If companies exporting to the UAE or to those other countries do not use oxo-bio technology such as Symphony’s d2w their products may be confiscated at the port.
  • Europe
    • The European Commission is currently undertaking an assessment on the impact of oxo-degradable plastics on the environment.  According to a recent amendment of the EU Directive on packaging and packaging waste, the results shall be presented by 2017, at the latest.
    • The European association representing the bioplastics value chain has asked all producers of additives claiming to make conventional plastics biodegradable to fully comply with the standard EN 13432, or to cease misleading references.
  • US
    • Studies performed by the Biodegradable Products Institute (BPI; New York) and by Michigan State University, in 2015, have also failed to demonstrate that the use of the technology leads to actual biodegradation.
    • In addition, the S. Federal Trade Commission has issued guidelines stating that unqualified biodegradable claims are acceptable only if they have scientific evidence that their product will completely decompose within a reasonably short period of time under customary methods of disposal.
    • S. National Advertising Division (NAD; New York) of the Council of Better Business Bureaus has recommended that advertisers discontinue claims such as “100% oxo-biodegradable” because such statements incorrectly suggest that a plastic will quickly or completely biodegrade with the help of these additives.
  • Others – Pakistan, Iran, Morocco, Yemen and DR Congo, have also completely or partially banned the use and import of plastic packaging unless it is oxo-biodegradable.

Standards and Certifications pertaining to these plastics with additives

Oxo-biodegradable plastic can be tested according to American Standard ASTM D6954-04 for Plastics that Degrade in the Environment by a Combination of Oxidation and Biodegradation. Also, according to British Standard 8472, or UAE Standard 5009 of 2009, or the French Accord T51-808.

The French Standards organisation, AFNOR, has also published XP T 54-980, for oxo-biodegradable plastics in agriculture. This is a very interesting standard for predicting the behaviour of an OXO-biodegradable plastic in case of littering. This test method provides an ecotoxicity testing method to ensure that residues in the environment, pending complete biodegradation, are not toxic.

In the case of enzyme degradable plastics, few manufacturers claim its biodegradability measured according to the ASTM D5511 test method. However, there exists no certifying bodies/organizations till date around the globe to approve the same. Here is the detailed review conducted by OWS, a research institute testing biodegradability and compostability of materials, which concludes that none of these enzyme degradable plastics adhere to what they claim. (http://www.ows.be/wp-content/uploads/2014/08/Report_Rev01.pdf )

Formation of Oxo-Biodegradable Plastics Federation (OBPF)

The negative publicity about oxo-biodegradable plastics has not deterred market players from focussing on research and development activities to study the appropriate usage of oxo-biodegradable products.

A new global industry coalition, the Oxo-Biodegradable Plastics Federation (OBPF), has been officially launched on 1st February 2016 to promote awareness regarding the availability of oxo-biodegradable products as an alternative to existing products. Some of the founding members of the industry coalition are Add-X Biotech, Wells Plastics Ltd., Willow Ridge Plastics Inc., and EKM Developments.

Market insights

According to market report by Business Standard in 2014, the sales of the plastic additives to enhance degradation saw a rise by almost 50% in the last five years alone, predicted to generate revenue of $57.8 billion by 2020 with an average growth rate of approximately 5% annually till 2020.

Bioplastic Guide estimates the key drivers, for the market share increase, to be the cost of a degradable plastic and the formation of favourable legislations by many countries in recent years.

So, how do we rate the oxo and enzyme degradable plastics?

Oxo degradable and enzyme degradable palstics cannot be considered as bioplastics as they neither “biodegradable” nor “compostable” under any standard test procedures. These additives merely enhance the rate of degradation of a conventional plastic like PET or PE when disposed off after its useful life.

  • Oxo/Enzyme -biodegradable technology has been developed to offer a cost-effective solution when compared to bioplastics and they will
    • perform in exactly the same way as conventional plastic
    • will look and feel like a conventional plastic
    • will not lose any of their original properties during their useful life
    • not pose any risks of methane generation when they are disposed off in landfills
    • can be disposed off in existing recycling streams
  • More than ten governments in the world have examined this technology very carefully and realised that oxo-biodegradable plastic offers a solution to plastic waste that escapes into the open environment and cannot realistically be collected. (Note– Only Oxo-biodegradable has been recognized and not enzyme degradable.)
  • However, though there are many favourable parameters, there have been very few successful test results mimicking the degradation claims by the manufacturers. Most of these test results are extrapolated or performed by unrecognized bodies. This has been the key contributor to all the confusions and the negative image on the oxo-degradable plastics.
  • Also, the use of misleading/false labels claiming to be “biodegradable” and “compostable” by these plastic additives, which is a false claim, have created a negative image among the consumers. The formation of a separate federation for oxo-degradation has led to instances where certain confusions over these plastics has been cleared.
  • Hence, we feel that the oxo-degradable plastics can fair better in the medium term, if not see a massive growth, with the introduction of clear and fair policies and regulations in which the by any of the developed nations and also manufacturers adhering to strict labelling and test procedures.

References and useful links

Benefits and challenges of oxo degradable plastics – http://www.ows.be/wp-content/uploads/2013/10/Final-Report-DSL-1_Rev02.pdf