The American Society for Testing and Materials (ASTM) and
the International Organization for Standardization (ISO) define
degradation as “an irreversible process leading to a significant
change of the structure of a material, typically characterized by
a loss of properties (e.g. integrity, molecular weight, structure
or mechanical strength) and/or fragmentation.” A general statement
regarding the breakdown of polymer materials is that it
may occur by microbial action, photodegradation, or chemical
degradation. All three methods are classified under biodegradation,
as the end products are stable and found in nature.
Many biopolymers are designed to be discarded in landfills,
composts, or soil. The materials will break down, provided that
the required microorganisms are present. Autochthonous soil
biota and water are generally all that is required, adding to the
appeal of microbially reduced plastics