ASIA - In the sixth of our special editorial series 'Bioplastics 101', we discuss the other "degradable plastic: oxo-degradable plastics, made using oxo-additives.
In recent years, one packaging material that has seen a surge in usage in Asia is oxo-degradable plastic – marketed by its manufacturers as an environmentally-friendly alternative material that has good end-of-pipe waste management benefits: its manufacturers claim that the material can degrade in landfill, or be re-used and recycled in the same recycling stream as conventional plastics.
The full article is available in the September 2015 issue of Packaging Business Insight Asia.
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Oxo-degradable plastics are essentially conventional fossil-based plastics that have an oxo-additive added to the basic polymer resin during the manufacturing process.
This oxo-additive causes the breakdown of the molecular structure of the fossil-based plastic material, i.e. degradation.
According to manufacturers of oxo-additives, the degradation takes place in two phases: The first degradation stage starts when the plastic containing the additive is exposed to oxygen, heat, UV light and stress. The oxo-additives act to break down the carbon-carbon molecular bonds in the plastics, leading to a lowering of the molecular weight and eventual loss of strength and other properties. By that stage, the manufacturers claim the material is chemically no longer a plastic but has become a material capable of bio-assimilation.
The second stage occurs after the molecular weight loss has occurred and the material is then able to be “completely biodegraded” by bacteria and micro-organisms, according to the oxo-additives manufacturers.
Stabilisers are added to the material to ensure that a sufficiently long shelf life is provided for each specific product, between 12 and 18 months, depending on the customer’s requirements and intended application.
The marketing material is appealing; one major oxo-additive manufacturer headquartered in the UK, Symphony Environmental Ltd, says its technology “takes ordinary plastic and makes it biodegrade… in the same way as a leaf.” In addition, the company claims its oxo-additive, d2w, “shortens the life of everyday plastic products so they don’t lie or float around for decades”.
Symphony Environment does clarify that oxo-degradable plastic is not intended to degrade in landfill, but adds that if it is landfilled it will continue to degrade so long as oxygen is present, but becomes inert under anaerobic conditions and does not emit methane, unlike biodegradable plastic which does emit a small amount of methane.
In addition, oxo-additive manufacturers claim that oxo-degradable plastics can be mechanically recycled, with no problems. And if they are incinerated, the energy within can be captured and used.
The sustainability of oxo-degradable plastics
In Asia, plastic grocery bags with printed messages that say, for example, “100% oxo-degradable” are an increasingly common sight.
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See other articles in the Bioplastics 101 series:
- Bioplastics 101: What are Bioplastics?
- Bioplastics 101: The Sustainability of Bioplastics Packaging
- Bioplastics 101: The Market for Bioplastics
- Bioplastics 101: Potential for an ASEAN Bioplastics Industry
- Bioplastics 101: Life-Cycle Analysis of Bioplastics
The full article is available in the December 2015 issue of Packaging Business Insight Asia. To find out more, click here.