Anoush Van der Kam
Introduction
Polyethylene Terephthalate plastics are important commercial polymers used in packaging, fabrics and the plastic bottles that have become ubiquitous in our daily lives. It is a popular polymer because it is 100% recyclable. However, the natural decomposition of PET bottles can take over 450 years. The resultant mass accumulation of plastic over the past century has had major environmental impacts.
Common polymers consist of hydrocarbons. Hydrocarbons are made of carbon compounds and hydrogen, bonded together in long chains. They are formed through a process known as polymerization.
Characteristics of PET plastics
Plastics are polymers with very high molecular masses. One of their key characteristics is that the hydrocarbon chains are entangled and not covalently bonded to each other. They are also thermoplastic, meaning that they can be reformed and remolded after undergoing heating. This allows plastic to be easily processed and recycled.
Plastics also have a crystalline structure, giving PET bottles a clear colour that is very useful in industrial applications.
Taken together, the properties of PET plastics give them useful properties such as being durable; being portable; providing chemical resistance (PET plastics are approved by the FDA for contact with food and beverages); and acting as effective barriers to gas and moisture.
However, the very same properties also make PET plastics difficult to decompose. After being initially discarded, plastics may remain in the environment for extended periods of time. As a result, the mass production and consumption of PET bottles has had detrimental effects on the environment. Case in point: the accumulation of microplastics in the Great Pacific Garbage Patch.
Microplastics: A near-invisible but very real danger
Secondary microplastics are formed from the degradation of larger plastic products via natural weathering processes. An example of such processes is exposure of plastic to UV rays, which causes it to fragment. Microplastics constitute 94% of all plastic pieces in the Great Pacific Garbage Patch.
Microplastics break apart further when ingested by marine life, releasing pollutant particles. The tissues of the unfortunate organism become contaminated, damaging its nervous and hormonal systems. Through the natural mechanism of food chains, these toxic pollutants spread throughout an ecosystem and can potentially end up in humans. The damage dealt by microplastics extends beyond marine creatures –– they also create a physical barrier which prevents corals from obtaining food. This significantly slows corals’ growth rates.
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