Polyethylene Essay

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QUESTION: Give the Preparation, Properties and Applications of any four POLYMERS
1. Polyethenics ( Vinyl Resins)
They are obtained by the polymerization of monomers containing the ethylenic bond (-C=C-)
I. Polyethylene ( PE )
Polyethylene is one of the simplest and most inexpensive polymers. It is a waxy, chemical inert plastic. It a thermoplastic formed by the addition polymerization of ethylene. There are two types of polyethylene
 Low Density polyethylene (LDPE)
By using free radical indicator, LDPE is obtained
 High Density polyethylene (HDPE)
Using ionic catalysts HDPE is obtained
• PREPARATION
It is obtained by polymerization of ethylene. The gas I first liquefied under high pressure and pumped into a heated pressure vessel, maintained
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Polytetrafluoroethylene ( TEFLON/FLUON/PTFE )
• PREPARATION
Teflon is linear polymer, it is also an addition polymer of terta fluoro ethylene CF2 =CF2 . it also an thermoplastic. Monomer tetra fluoro ethylene is obtained by treating chloroform with HF to get di-fluoro chloro methane, which on pyrolysis gives the monomer
Emulsion polymerization of tetra fluoro ethylene in the presence of any peroxide initiator gives TEFLON
• PROPERTIES
 Teflon is linear polymer with a high degree of crstallinity
 Its flow temperature is high
 It is practically insoluble in all solvents
 It is chemically inert and not attacked by acids, alkalis, oxidizing and reducing agents
 It is not wetted by oil or water
 It has high resistance to impact wear and tear
 It is thermally stable and has a good electrical insulating property
 Because of all the above properties it is known as WONDER PLASTIC
• APPLICATION
 Because of its excellent insulating capacity it is used for the insulation of generators, motor, transformers and other electrical appliances
 Oil and water don’t wet Teflon and this property is used in coating non-stick cooking utensils, bakery trays, frying

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