Synthetic polymers in our daily life
list of synthetic polymers
examples of synthetic polymers and uses
synthetic polymers in medicine
Polymers in our daily life
The word polymers are derived from the Greek poly means 'many' mer means 'part'. So the polymers are the compounds having long chains of repeating units of specific molecules. These are also called macromolecules. Polymers have different natures depending upon the types of atoms of different elements i.e.,
- Inorganic Polymers (Giant molecules) e.g diamond, graphite, sand)
- Organic Polymers
Lipids, proteins, carbohydrates, nucleic acid etc.
Plastic, synthetic fibers,
Rubbers etc.
synthetic polymers in industries
Polyethylene is formed by the radical polymerization of ethylene /ethene molecules in the presence of peroxides as catalysts. Molecular weight is of range 14,000-1,400,000 (corresponding to 500-50,000 ethylene units).As the molecules of straight-chain polyethylene molecules are held together by weak van-dar waal's forces so the polyethylene is flexible and soft. Flexibility increase with the increase in temperature. This way it is possible to form polymers, such as polyethylene into various shapes by heating and then molding while they are relatively soft. Such materials are called Plastics. Similarly, a large variety of plastics can be made by the polymerization o derivatives of ethene. The substitute attached to the double bond of ethylene is methyl (-CH3), chloride (Cl), Aryl (-C6H5), cyanide (CN), etc.
polyethylene is a common sight in the streets in the form of shopping bags.
Polypropylene is formed by the radical polymerization of propylene.
Polypropylene fibers are used in carpets, automobile tires, consumer items, such as luggage, appliances, etc., and packaging materials.
It is also known as PVC formed by the radicle polymerization of vinyl chloride.
polyvinyl chloride is a hard resin: and is used to make pipes, rods, and compact discs. However, if high boiling esters, such as bis-2-Ethylhexyl phthalate are added to the polymer formulation, it becomes soft.
The softer PVC is used for initiation leather upholstery, plastic raincoats, shower curtains, garden hoses, and plastic squeeze bottles.
It is made by polymerization of tetrafluoroethylene in an aqueous suspension. The reaction is highly exothermic and water helps to dissipate the heat that is evolved. It is marketed as Teflon.
Teflon is highly resistant to chemicals and organic solvents and low coefficient of friction. It is thus used in greaseless bearings, gaskets, and fittings, and in special situations that require a substance that is highly corrosive chemicals. It is also used for the nonstick coating of cooking utensils.
It is formed by radicle polymerization of Styrene.
Polystyrene is a hard brittle and somewhat brittle material that is a good electric insulator. It is an inexpensive plastic and is used to manufacture many familiar household items, and radio and television cabinets.
It is formed by the radicle polymerization of acrylonitrile in the presence of a mixture of ferrous sulfate and hydrogen peroxide which react together to produce hydroxyl radical to initiate the chain reaction. polyacrylonitrile decomposes on melting, so melting spinning cannot be used for the production of fibers. However it is soluble in N, N-dimethylformamide, and this solution can be spun to give fibers, commonly known as Orlon or Acrilon.
Fibers produced this way are used as wool substitutes in making sweaters, blankets, and carpets.
- Poly(methyl methacrylate)
It is synthesized by radical polymerization of methyl methacrylate. This polymer is transparent plastic with excellent optical properties. When cast in sheets, it is used as a glass substitute. It is marked under the names
Lucite, Plexiglas, and
perspex.Diene Polymers
These polymers are obtained by the radical polymerization of Butadiene and other conjugated dienes. It is a synthetic rubber and is used in automobile tires.
It is synthesized in industries by radical polymerization of isoprene. It is also a rubber but differs in properties from natural rubber. By adding Ziegler-Natta catalyst its properties can be identical to natural rubber.
It is obtained by the polymerization of neoprene. It is a synthetic rubber. However, neoprene is inferior to natural rubber in some properties but superior in its oil resistance to oil, gasoline, and other organic solvents.
Some of the uses of neoprene include electrical insulation, conveyor belts, hoses, and weather balloons.
An important polymer that is synthesized industrially is polyethylene terephthalate. It is obtained when dimethyl terephthalate and ethylene glycol are heated together and methanol that is eliminated is distilled out from the reactor. It melts at 270 degrees centigrade. Polyesters are the major synthetic fibers.
It is synthesized by the polymerization of an equimolar mixture of adipic acid and 1,6 hexane diamine is allowed to give a 1:1 salt which on heating yield a polyamide, known as nylon 6, 6. It can be converted into fibers by further processing operations.
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