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Standard Guide for Exposing and Testing Plastics that Degrade in the Environment by a Combination
The American Society for Testing and Materials (ASTM
International) acknowledges the oxo-biodegradable technology in ASTM D
6954 C04. This is a standard guide specifically developed for plastics
that degrade initially by an oxidative process and subsequently
biodegrade. D 6954 prescribes the tests to be done in order to rate
these materials in terms of their ability to degrade, biodegrade and to
assess their eco-toxicity impact to the environment of disposal.
The ASTM6954 guide provides a framework or a road
map to compare and rank the controlled laboratory rate and degree of
physical property losses of polymers by thermal and photo oxidation
processes and biodegradation, and ecological impacts after degradation
in defined applications and disposal environments. Disposal
environments range from exposure in soil, landfill, and compost where
thermal oxidation may occur, and to land cover and agricultural use
where photo-oxidation may also occur.
This standard guide uses established ASTM standards in three tiers
Tier1: for accelerating and measuring the loss in properties and
molecular weight by both thermal and photo-oxidation processes, and
other abiotic processes;
Tier2: for measuring biodegradation;
Tier3: to assess ecological impact of the products from these processes;
Go to Document Library to download testing report
The Tier 1 conditions selected for thermal oxidation
accelerate the degradation likely to occur in a chosen application and
disposal environment. The conditions should include a range of humidity
or water concentrations based on the application and disposal
environment in mind. The measured rate of degradation at typical
oxidation temperatures is required in order to compare and rank the
polymers being evaluated in that chosen application to reach a
molecular weight that constitutes a demonstrable. By way of example,
accelerated oxidation data must be obtained at temperatures and
humidity ranges typical in that chosen application and disposal
environment, e.g. in soil (20C to 30C), landfill, 20C to 35C) and
composting facilities (30C to 65C). For applications in soils, local
temperatures and humidity ranges must be considered as they vary widely
with geography. At least one temperature must be reasonably close to
the end use temperature, but under no circumstances should this be more
than 20C. It must, also, be established that the polymer does not
undergo a phase change, such as glass transition temperature (Tg). The
residues resulting from the oxidations are then exposed to appropriate
disposal or use environments in standard biometric test methods to
measure the rate and degree of biodegradation (Tier 2). The data
generated under Tier 1 evaluation and the determined time for the
biodegradation in the chosen environment (Tier 2) allows ranking
relative to other polymers evaluated under similar environmental
conditions with this guide. The degree and time for biodegradation
should be consistent with ASTM methods and any residues from the
intermediate oxidation stage and from biodegradation must be shown to
be environmentally benign and not persistent (Tier 3).
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