Degradability and Biodegradability Claims
EPI’s TDPA® provides a means for rendering conventional plastics degradable, and ultimately biodegradable, within a reasonable and controlled time-frame. TDPA® is added in small quantities (typically 2-3%) to the conventional plastic during the manufacturing process and allows totally degraded plastic products such as polyethylene carrier bags to biodegrade within 24 - 36 months, when disposed of in an appropriate environment.
For plastics, degradability refers to change in chemical structure and loss in mechanical properties caused by a specific environment, resulting in the plastic breaking down into small fragments. Biodegradability results from the actions of naturally occurring micro-organisms such as bacteria, fungi and algae and results in the plastic fragments being consumed. Conventional plastic materials are extremely resistant to degradation and biodegradation and persist in the environment for decades, or even centuries.
How Does TDPA® Work?
TDPA® works by way of the oxo-biodegradation process, which occurs in two stages. In the first stage, TDPA® accelerates the plastic degradation process by several orders of magnitude, whereby the long polymer molecules are reduced to shorter and shorter lengths and undergo oxidation (oxygen groups attach themselves to the polymer molecules). This process is triggered by heat (elevated temperatures found in landfills or composting), UV light (a component of sunlight) and mechanical stress (e.g. wind or compaction in a landfill). Oxidation causes the molecules to become hydrophilic (water- attracting) and small enough to be ingestible by micro-organisms, setting the stage for biodegradation to begin.
In the second stage, biodegradation occurs in the presence of moisture and micro-organisms typically found in the environment. The plastic material is completely broken down into the residual products of the biodegradation process. As micro-organisms consume the degraded plastic, carbon dioxide, water, and biomass are produced and returned to nature by way of the biocycle.
EPI prides itself on being the pioneer in oxo-biodegradable technology and, as such, has been the trailblazer in terms of proving the technology. When it comes to validation of biodegradability, EPI can cite numerous independent, peer-reviewed studies evaluating plastics containing TDPA® that conclusively demonstrate biodegradability. Here are a few excerpts from these studies:
- LDPE-TDPA oxidized samples undergo significant biodegradation (50 – 60% by carbon dioxide evolution) over a period of 18 months as mediated by soil micro-organisms” - Chiellini et. al., Polymer Degradation and Stability 81 (2003) P. 350
- LDPE-TDPA formulations are effective in promoting the oxidation and subsequent biodegradation of polyethylene in soil environments” - Chiellini et. al., Polymer Degradation and Stability 81 (2003) P. 351
- SEM evidence confirms that microorganisms build up on the surface of the polymer…. The surface of the polymer after biological attack is physically weak and readily disintegrates under mild pressure.” – Bonhomme et. al., Polymer Degradation and Stability 81 (2003) P. 451
To learn more about the science behind EPI’s technology go to scientific publications.