A polymeric molecule is not rigid like a straight rod , but it is a very long and flexible chain , it
can change form easily because many in dependent vibrations and rotations of the
individual atoms that compose the molecular chain .
Long , flexible polymeric chain can change their configuration and lengths easily when a
stress is applied .
( There are special cases such as special liquid crystalline polymers that have a rigid rod like
molecule ( the aramid fibers ) .
Elastomer is a special polymer which have cross – linked chains and the number of
configurations available is very large . Elastomers show very high reversible non – linear
extensions ( 5 – 700 ) % in response applied stress .
Vulcanization sulfur to form cross – linking ( the existence of a network ) to avoid chains