Biodegradable Plastic
Frequently Asked Questions

Q. What is the difference between compostable and oxo-biodegradable?
A.  Compostable products must degrade in the time frame prescribed by ASTM D 6400 test. The most popular compostable resin is polyactic acid (PLA).We manufacture oxo-biodegradable polyethylene recognized by ASTM D6954 – 04. Our products meet 3 of 4 requirements D 6400. Conversion of polymers into smaller elements does not occur rapidly enough to meet the ASTM D 6400 standard.


Q. Can you make a film or bag that is a blend of PLA and polyethylene?
A. No, the resins are too dissimilar.


Q. How do you know it works?
A. very application is put through an accelerated aging test replete with a control which has no biodegrading agent. A thorough analysis is conducted afterwards. In addition to measuring the changes in physical properties, we measure the change at a molecular level through infrared analysis.


Q. Exactly what will I look at after film degrades to molecules?
A. PE containing TDPA will first undergo degradation by reacting with oxygen to form molecular fragments that are water-wettable and which will be ultimately biodegradable by action of micro-organisms to produce water, carbon dioxide and biomass.


Q. How much percent reduction will there be with oxo-biodegradables after 10 years?
A. TDPA-PE would have degraded and biodegraded by this time. In a typical landfill that contains significant microbial activity due to the presence of organic waste materials such as food wastes, garden wastes, paper, etc., TDPA-PE would have undergone biodegradation and produced by-products which are part of the eco-system.


Q. How much percent reduction will there be with oxo-biodegradables after 4 years?
A. If it is a controlled study, then dates of disposal and times to retrieve products would be part of the protocol. If samples are randomly dug, then such information has to be provided by the landfill authority. Many studies have been conducted to demonstrate the degradation of TDPA modified plastics in landfills in UK, Canada, China and USA. In a particular study by MJ Carter in UK, it was shown that PE manufactured with TDPA will mechanically and chemically break down over a period of several months in an operating landfill. The PE film was buried down to 3 meters deep and the TDPA-PE was found to have totally degraded in 10 months including the winter period. Weight average molecular weight was performed by an independent testing laboratory (RAPRA) and was shown to reduce drastically from 115,000 to 4,250. This indicates scientifically that the PE has totally degraded to significantly much smaller molecules which are susceptible to biodegradation. Unless otherwise specified, we design films to begin biodegrading two years after the product has been used and sent to the landfill.To properly time the degradation, each case must be dealt with individually. In other words, each resin blend requires different additives in varying percentages.


Q. I don’t see a benefit to something that is not going to be compostable after 3 years.
A. TDPA-PE will degrade within 12-24 months in landfill when exposed to oxygen, sunlight or heat and mechanicals stress present in landfill. As explained above, these degraded plastics will ultimately biodegrade (within 2-3 years) into products which are part of the eco-cycle. Plastics containing TDPA undergo aerobic biodegradation which converts the carbon in the plastics into carbon dioxide instead of methane which is at least 20 times more harmful as a greenhouse gas.


Q. Does the biodegrading agent alter the performance or appearance?
A. No, our biodegradable films have the same optical and physical properties as ordinary polyethylene films.

 

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