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 …show more content…
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