Creation of Polyethene and HDPE
J. Paul Hogen and Robert L. Banks Image Source: http://www.mpponline.in/plastics-innovators-j-paul-hogan-and-robert-l-banks-inducted-into-plastics-hall-of-fame/
In 1935, polyethylene was created when Eric Fawcett and Reginald Gibson discovered that benzaldehyde and ethylene could be combined under extremely high pressure to form solid polymers. In the 1950s, HDPE was created when J. Paul Hogen and Robert L. Banks (image above) discovered that ethylene and propylene could be combined with the help of a catalyst into solid polymers. Ethylene and propylene were originally by-products of the refining process of natural gas. By setting up experiments, Hogen and Banks discovered that chromium oxide could produce a crystalline, solid material, instead of the liquid that was expected if nickel oxide was used. Polyethylene had actually been invented less than two decades ago in the 1930s, but extremely high pressures were needed for the production process. With the use of a chromium catalyst, HDPE could be produced at a much lower pressure. This proved to be the turning point in the commercial production of polyethylene, as it could now be synthesized at low temperatures and pressure. The first commercial use of HDPE was the insulation of radar cables during World War II.
Modern Uses of Plastics, HDPE and Its Implications on the Environment
Plastic has definitely been an important product throughout the entire world. However with over usage of this product, there will be many environmental concerns that will come along with it. What makes plastic such an attractive material for all would be the fact that it is durable. We can use plastic for a relatively extended period of time. On the down side, being a durable material means that it will degrade slowly. Toxic fumes will be released if we burn plastic to try to get rid of it.
Although manufacturing of HDPEs is relatively cheap, an enormous amount of chemical pollutants (chromium oxide, benzoyl peroxide, hexane, and cyclohexane) and fossil fuels will be involved in the production of plastic.
Chromium oxide is suspected carcinogen and damaging to the liver and nervous system.
So much for all the cons, some people have actually argued that plastic has a positive impact on the environment. Plastic has been used to lighten the weight of cars, hence, less oil would be needed to mobilize cars and eventually lower the carbon dioxide emission. Most notable contribution of plastic would be the use of plastic containers which have helped us dispose toxic waste products in a safer manner.
Since the 1990s, plastic recycling has become a notion in a bid to save the environment. The Plastic Bottle Institute of the Society of Plastics Industry created a method to mark plastic bottles for people to determine the type of plastic it is made of. It is essentially a triangular symbol consisting of three arrows with a number in the middle and alphabets on the outside of the symbol to distinguish the type of plastic used. One example would be HDPE, which is what our group focuses on.
Due to the many different types of plastic available, recycling has not been an easy feat as the process of sorting plastics could not be automated. Plastic recycling is relatively labour intensive as well.
Today, there have been researches in place for biodegradable plastic. This research aims to develop a type of plastic which can degrade naturally upon being exposed to sunlight. Through the mixture of plastic with starch, plastic can be made to degrade much easier. Unfortunately, this method does not result in plastic to degrade completely.
One other development would be a genetically engineered bacterium which has the ability to synthesize biodegradable plastic. However, this technology is very costly at this stage. The down side of this is that carbon actually gets locked up in the biodegradable plastics and can be released into the atmosphere as carbon dioxide.
Furthermore, these biodegradable plastics require sunlight to break down. The plastics which are buried in landfills will still take a long time to degrade as they are not exposed to the sun. As such, these biodegradable plastics will only be degraded if they are disposed as roadside litter.
American Chemical Society. (1999). Discovery of polypropylene and the development of a new high-density polyethylene. Washington, DC: American Chemical Society Office of Communications.
Plastic and the Environment. (2015, January 1). Retrieved March 11, 2015, from http://www.plasticsindustry.com/plastics-environment.asp