Woolworths (and presumably Coles too?) make a
big deal about their alleged ecologically responsible
shopping bags. But... are they biodegradable?
No, because they're made from polypropylene.
And they're made in Vietnam!
Degradable plastics are divided into photodegradable
plastics, biodegradable plastics, etc. Commonly used
degradable plastics include PHA, APC, PCL, and so
on. Polypropylene (PP) does
not belong to the category
of degradable plastics.
From the above description of degradable plastics, we
know that the fundamental difference of degradable
plastics is that they can be degraded in the natural
environment, and these degradable substances are
harmless and don't cause any harm to the environment.
PP particles are generally combined with antioxidants
and degradants (for cracking, embrittlement, and
flaking) which are difficult to degrade.
PP takes
20-30 years to degrade, and in the process
will release toxins, polluting the environment and soil.
Apparently, changing the carbonyl content of PP can
make the degradation period of PP plastics around
60-600 days. Adding a small amount of photoinitiator
(to convert absorbed light energy or UV into chemical
energy) and other additives to PP plastic can quickly
degrade it—providing
it's not buried.
So, how do we find out exactly what sort of PP is being
used by Woolworths? Any floor staff just respond with
a blank look, and its HO has no idea either.
This raises an obvious question: Are we being conned?
Are their so-called "green" bags
genuinely biodegradable
and ecologically friendly?