Polyethylene is a polymer
consisting of long chains of the monomer
ethylene. The ethene
molecule (known almost universally by its common name ethylene) C2H4
is CH2=CH2, Two CH2
groups connected by a double bond. Polyethylene is created through polymerization of ethene. It can be produced
through radical polymerization, anionic addition polymerization,
ion coordination polymerization
addition polymerization. This is because ethene does not have any
substituent groups that influence the stability of the propagation head of the
polymer. Each of these methods results in a different type of polyethylene.
Polypropylene is a thermoplastic
polymer, made by the chemical industry and used in a wide variety of
applications, including packaging
Polyester is a category of polymers
which contain the ester functional group
in their main chain. Polyesters may be produced in numerous forms such as
fibers, sheets and three-dimensional shapes. Polyesters as thermoplastics may change shape after the
application of heat. Polyester fibers have high tenacity and low water
absorption and minimal shrinkage in comparison with other industrial fibers.
Polyvinylidene chloride is a polymer derived from vinylidene chloride. Polyvinylidene
chloride is applied as a water-based coating to other plastic films such as
biaxially-oriented polypropylene (BOPP) and polyester (PET). This coating increases the
barrier properties of the film, reducing the permeability of the film to oxygen and flavors and thus extending the shelf life of the food inside the package.