As the chemical properties of plastic plays a crucial role in explaining how plastics brings about environmental pollution, this post will further expand on the chemical properties of plastic, focusing on how its chemically inert and hence non-biodegradable.
To make this post more digestible for the casual readers, i have decided to sum up the chemical properties of plastic into 4 important points:
- More Than One Type Of Plastic
“Plastic” is a ‘catch-all’ term used to describe polymer of high molecular mass. There is more than one type of “plastic” being synthetically produced.
It is important for us to identify the types of plastic as this allows us to know if its recyclable and also what are the by-products that would be released if we were to breakdown the plastic waste (to be elaborated on).
Plastics are ridiculously durable. Plastics are made up of long chain of molecules (polymer) containing repeated units of carbon atoms (monomer). These polymers has extremely strong carbon-carbon bond with with each other. Because of this inherent molecular stability, plastics do not breakdown into simpler components easily.
Plastics sold commercially are intentionally designed to be resistant to chemical decomposition. The chemical bonds that hold the molecules are stronger than nature’s power to take them apart. Micro-organisms in the soil and water are thus unable to attack and breakdown plastic products.However, plastics still do breakdown over a long period of time. The Marine Conservancy has published that the estimated decomposition rates of most plastic debris found on coasts are:
- Foamed plastic cups: 50 years
- Plastic beverage holder: 400 years
- Disposable diapers: 450 year
- Plastic bottle: 450
- Fishing line: 600 years.
- Photo-degradation VS Bio-degradation
As mentioned in the previous point, plastics are mostly resistant to biodegradation as microbes that break down other organic products are unable to breakdown plastic polymers due to their strong C=C.
However, plastic can be fragmented with the effects of UV, being broken down by light into smaller and smaller fragments over time. The process of plastics fragmentation is assisted by wave, sand action, and oxidation.
These small plastic fragments (aka mermaid’s tears) are not absorbed into the natural system, they just float around within it. The photo degradation of plastic debris worsen plastic pollution as microscopic and invisible plastic fragments are eaten by even tinier marine organisms, therefore entering the food chain insidiously and ineluctably. The bioaccumulation of plastics in the foodchain is expected to bring about sever biological harm in humans… (which brings us to the next point)
- Different types of plastic breaks down to produce different types of toxic compounds that are harmful to the living organisms.
In the next few posts, we will delve deeper into the impact of plastic pollution on land, air and sea environment. Cya.