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Polyethylene is derived from natural gas feedstock. The catalyst breaks polyethylene into shorter chain molecules incorporating oxygen as an organic functional group – alcohols, carboxylic acids, aldehydes, ketones, esters and are able to be consumed by micro-organisms and converted into water, carbon dioxide and biomass.
The FDA approved catalyst does not sacrifice processing or performance characteristics. In other words, we can “retrofit” existing products to degrade rapidly after the useful service life compared to polyethylene’s approximate 300 year half life. The exact time frame depends on what is referred to as “disposal media” such as landfill, compost or incineration.
As recognized by the American Society for Testing and Materials, ( ASTM International ) standard guide D6954-04,oxo-biodegradable plastics return to the ecosystem via a 2-stage process.
The first stage is called degradation – a chemical or abiotic step where the plastic molecules react with ambient oxygen and are broken into much smaller hydrophilic ( water-loving / water- wettable ) molecules. The triggers for this reaction are heat, ultraviolet light and mechanical stress. The partially disintegrated molecules are now amenable to biodegradation. Next, after consumption by naturally occurring micro-organisms, what remains is CO2, H2O and a small quantity of minerals and biomass.
The degradability rate is the time between the “kick-off time” ( initiation of the oxidation process) and “end-degradation point“ ( time when the sample becomes totally degraded ) in the end-disposal environment ( e.g. landfills ). The time frame varies depending on exposure to triggers ( heat, ultraviolet light ) in differing ambient conditions. Studies have shown that there is enough oxygen present in the top 15 feet of a landfill to sustain the degradation reaction.
To ensure performance of the packaging, we must be conservative about the initiation point of degradation. This is reliably interpolated with standard testing conditions. |
