Running head: PLASTIC
Literature Review: Plastic Pollution and Hormone Disruption
West Coast University
1. Plastics Types and Chemical Bonds
Plastics are materials made from various elements including sulfur, carbon, nitrogen,
hydrogen, chlorine and oxygen. The manufacture of plastic imitates the properties natural
materials such as rosin and horn in having high molecular weight. The primary chemical of
plastics is obtained from coal, natural gas, or oil. Carbon atom is the basis of most plastics. The
carbon atoms connect to sulfur, nitrogen, hydrogen, chlorine or oxygen to form plastic. The
carbon atom may connect with two atoms as in the case of polyethylene or more as in the case of
nylon. The group of atoms is called a monomer. Monomers are combined to form polymers or
plastics. Monomers make identical units called unit cells which repeatedly connect to form long
chains (American Chemistry Council, 2017).
There are two types of plastics that are made: thermoplastic and thermoset. Polymer
consisting of one-dimensional long chains of unit cells is called thermoplastic. Thermoplastics
can be melted and constitute about 92% of the plastics. If the polymer is a network of two or
three-dimensional chains, it is a thermoset plastic. Thermoset plastics cannot be melted and are
therefore used before curing. Bathtubs and epoxy adhesives are examples of thermoset plastic
(American Chemistry Council, 2017).
The difference in properties determines the application of the two types of plastic. The
molecules in thermoplastic are held by weak secondary bonds that when subjected to heat cause
the material to soften. Thermoplastic can be reshaped in the softened state by pressing, molding,
or extrusion. There are wide applications of thermoplastics: Polyethylene is commonly used to
make packaging film, water and soda bottles, and electrical insulation; polypropylene is used for
external prostheses, vehicle bumpers, and carpet fibers, and polyvinyl Chloride (PVC) is useful
in making vehicle panels, floor and wall coverings, and cable sheaths (American Chemistry
2. Biodegradable versus Non-biodegradable
When a material is degradable, it m...
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