Positive uses of polyethylene and polyethylene derivatives:

• Polyethylene fuel tanks
• Teflon (poly-tetrafluoroethylene) (PTFE)
• Plastics

Polyethylene is a main component of Plastic. Hence, on this page, we shall discuss the Impact of Plastic on the Environment.

Environmental Impact

a) Positive:

Plastics being extremely malleable and durable, are able to replace traditional materials in mainly construction of structures and clean energy apparatus.

Structures:
Recycled plastics from bottles or plastic bags could be remolded into rigid, sturdy and eco-friendly masonry that can be used in constructing Buildings. Compared to traditional material such as cement-bricks, plastics building blocks that consists of recycled PVC and PE-HD are lighter, is 85% more efficient to produce, emit 95% less greenhouse gases and use no water during the manufacturing process.

Figure 3.1 A structure made from plastics

Clean energy apparatus:
Plastic rotors on windmills produces a 33% savings on Green house gases, a huge 140 times use benefit in comparison to production needs and Carbon fibre-reinforced plastics in the near future would be the default construction material for wind blades.

Solar energy is another area for plastics innovation. Usually made of inflexible silicon, solar panels could be created using plastic photovoltaics instead in the near future. Plastic photovoltaics are cheaper and more malleable, meaning that future solar panels could be created using the wallpaper concept and be attached to any surface.These schematics would likely be used on a small scale, but its effects would be world-changing. Plastic photovoltaics offer a 25% saving in green house gases emission and provide a 340 times higher saving as compared to what they consume during production.The solar cells itself has also started to shift to plastics, being made up of 98% plastic, allows them to be  cost-efficient and flexible, and they absorb up to a record 96% of incident sunlight.

b) Negative:

Pollution of Plastic leads to many hazardous and ecologically damaging consequences.

For one, there is the danger in the entanglement or indigestion of plastic items in small marine animals at sea or mammals on land.

• Entanglement in plastic causes restriction in movement, and sometimes even breathing. Hence, if these marine life are not be able to break free from the plastic and they may die.
• Marine birds are especially susceptible to ingestion of plastic objects that they may mistake it for food. This leads to decreased feeding stimuli, intestinal blockage and may sometimes cause reproduction problems.

In addition, they destroy the natural beauty of the beaches and the tourism industry will be adversely affected.
These Plastic particles in the ocean have been shown to contain quite high levels of organic pollutants.

Toxic chemicals, such as polychlorinated biphenyls (PCBs) and nonylphenol (NP), are commonly found throughout oceanic plastic debris. These compounds increase the risks associated with ingestion of plastic debris by animals, and additionally, many of these compounds can undergo significant biomagnification and in turn might potentially pose a direct risk to human health.
These toxic agents have been found to be linked to many health issues, including developmental impairment (neurological impairment, growth abnormalities and hormonal imbalances), cancer, endocrine disruption, neurobehavioral changes, and breast cancer.

Figure 3.2 Plastics waste

As shown in Figure 3.2, it is not aesthetically pleasing to have rubbish found on the streets near our homes or in the rivers.

Bio-Degradation of Plastic

Generally, plastics do not naturally degrade(break down) when released into the environment. This is due to the high stability and durability of polymers.

The four mechanisms by which plastics degrade in the environment are photodegradation, thermooxidative degradation, hydrolytic degradation and biodegradation by microorganisms.

Natural degradation of plastic begins with photodegradation, which leads to thermooxidative degradation. Ultraviolet light from the sun provides the activation energy required to initiate the incorporation of oxygen atoms into the polymer. This breaks the plastic into smaller and smaller units, until the polymer chains have low enough a molecular weight to be metabolised by microorganisms. These microbes either convert the carbon in the polymer chains to carbon dioxide or incorporate it into biomolecules.

However, it may take more than 50 years for the entire plastic to degrade. In the ocean, the photodegradative effect is significantly decreased in seawater due to the lower temperature and oxygen availability and hence the rate of hydrolysis of most polymers is insignificant in the ocean, reducing the rate of degradation.