 |
| A symbol showing that a plastic shopping bag is photodegradable |
A plastic shopping bag is the bag
stores give you to help you carry the things you buy in a store. The plastic shopping
bag helps you carry the bottle of milk, the fruit juice, the butter, the
vegetables, bottle of whisky, the bread, the chicken or beef you buy from the
store. How do you know that the plastic shopping bag you are leaving the store
with is degradable or biodegradable? How do you make the differentiation
between them so as to patronize a more environmentally friendly plastic
shopping bag?
In my past several posts, I have
tried to show how a product can be identified as environmentally friendly. One
clear way you can do such identification is by the symbols on the products. In
this post I am going to focus on the differentiation in degradability of the plastic
shopping bag.
Last Friday, November 25, 2016 at
Shoprite, Osu- Accra, on Oxford Street (where I normally shop), there was a
Black Friday. I took the opportunity to go and buy some stuff on that day. I
passed another store, Koala Supermarket, also on the Oxford Street to buy something.
I got home with my plastic shopping bags and by chance I realized that the bags
from the two different stores are degradable bags! Notes on the bag say so. The
two stores are reputable stores in the country. The bags bear the symbol I have
presented in this post. By the notes and symbols on the carrier bag you will
know whether a plastic shopping bag is degradable or biodegradable, and thereby
determining your choice and patronage. There are many different symbols in the
world indicating that a plastic carrier bag is degradable. The plastic shopping
bags I brought home from the two stores are specifically photodegradable.
Photodegradable simply means when the carrier bag is exposed to the sunlight
over a period of time it breaks down.
MAKING OF
PLASTIC
There are various kinds of
degradable plastic shopping bags. How a plastic shopping bag degrades is
determined by the chemistry it undergoes. This post is going to focus on two
types of degradation- the degradable and the biodegradable. Before I delve into
the two types of degradation let me deal briefly with the chemistry of plastic
as a background to and facility for explaining degradation by way of the two
types.
Plastic is made from natural
products such as crude oil, natural gas and coal. Plastic chemically,
basically, is made from the atoms of hydrocarbons. The making of plastic starts
with the distillation of oil which breaks the oil down into fractions or simple
forms. A fraction is made up of chemical
compounds of hydrogen and carbon, differing in molecular size and structure.
One of the fractions called naphtha is the key to the production of plastic.
Two or more atoms joined together by chemical bond to form a molecule. An
example of molecule is oxygen (O₂). An example of molecules is water (H₂O) - two
atoms of hydrogen and one atom of oxygen. Small molecules are called monomers. Enlarged
small molecules (monomers) with many subunits form a polymer. Monomers like
ethylene and propylene combine to form a large chain of molecules in the
polymerization process. The end result is polymer. The polymerization process
gives plastic its elastic and pliable nature. In essence polymer is the
chemical nature of plastic.
DEGRADABLE
When I brought my shopping bags
home, and realized they are degradable I did not then know the degree to which
it was environmentally friendly. All plastic shopping bags are degradable in
that the plastic can be broken down. Normal plastic bags can lie around for
hundreds of years before eventually breaking down. The plastic shopping bags
lying around for hundreds of years make the environment dirty. The plastic
shopping bags with the photodegradable symbol, as shown in this post, breaks down
on exposure to sunlight over a relatively shorter period of time by the
integration of an additive into normal plastic. The plastic shopping bag breaks
into pieces, and remains plastic in the environment nonetheless. The plastic, in this case does not lie around
or is it blown around like the normal plastic materials (plastic that lie
around for hundreds of years). There is another way of degradation through
oxidation, called Oxo-degradable. This type of plastic break down through the
agent of oxygen. Oxygen is introduced into the polymer of hydrogen and carbon
thus inducing degradation.
BIODEGRADABLE
Plastic shopping bags that are
biodegradable return the elements in them into nature. I have already indicated
that plastic is made from hydrocarbons. In the process of biodegradation,
through the agency of microorganisms, the carbon in the plastic is returned
into the carbon cycle for the benefit of other life forms, for that matter the
environment. This is truly environmentally friendly. This is not the case with
plastic shopping bags branded degradable. Another type of biodegradable plastic
is compostable plastic.
KEY POINTS
All plastics are degradable, one
way or the other.
Plastic shopping bags branded
“degradable” merely break down on exposure to sunlight or through oxidation,
remaining in the environment as plastic, still. They do not lie around for a
long time making the natural environment look dirty though.
Plastic shopping bags branded
“biodegradable” not only break down, the elements in the plastic, through the
agency of microorganisms, go back into nature.
Compostable plastic is also
biodegradable.
Plastic shopping bag branded
“biodegradable” is better than a plastic shopping bag branded “degradable”.
PARTING SHOT
Remember it is still a business of ensuring
a clean and balanced natural environment in a sustainable way as far as this
blog goes. Useful as plastic is to the culture of our times, it is also obvious
how plastic waste has endangered our environment, and indeed our very lives.
One key contributor to the plastic that gathers in the gyres of the oceans of
the world is plastic shopping bags. Weekly, monthly, perhaps daily, we go
shopping and the stuff we buy are put in plastic bags. You can imagine the
number of people in the entire world leaving stores with their shopping bags
every week. Since managing plastic after we have used them is a major problem, it
is then of critical importance that we take pains to be choosey in the kind of
shopping bag we use. I intend this post to serve as a facility of differentiation
and choice for the sake of a wholesome natural environment.
Comments
Post a Comment