The red lines represent the cross links between the chains.
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Structure of Polymers.
Polymers may be classified as thermosoftening or thermosetting.
Thermosetting polymers have their chains cross linked
by covalent
bonds.
The polymer is originally placed into a mould to form the desired
shape.
The polymer is then heated (or initiated with
uv light) and chemical
reactions occur to form the cross
links between the chains.
The resulting three dimensional
solid structure cannot then be changed.
Further heating will not cause the polymer
to soften or change shape
(unlike thermosoftening polymers).
Examples of thermosetting polymers are
1. Melamine - used in
furniture.
2. Bakelite - used for
saucepan handles and electric light
fittings.
3. Epoxy resins - used in many
glues.
The picture below shows a
typical structure for a thermosetting polymer.
The red lines represent the
cross links between the chains.
Headings Polymers Search Questions 
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Copyright © 2008 Dr. Colin France. All Rights Reserved.