Plastic production begins with refining oil, when certain petrochemicals are separated out. In one processing method, a key chemical, naphtha, is put under enormous heat to break up its hydrocarbon compounds. The resulting monomers are then chemically arranged to produce long repeating chains.
The polymer chains are combined with various materials to make plastic resins with different characteristics. Two of the most widely produced types of thermoplastic polymer resins are polyethylene and polypropylene.
Polyethylene (PE) is used for electrical insulation, medical equipment, packaging, films, tubes, or laminates, among other products.
Polypropylene (PP) is commonly used in plastic injection molding, needed to produce durable plastic parts such as automobile bumpers, for example.