Chemistry Reference
In-Depth Information
POLYMER STRUCTURE
Branched polymer
Crosslinking
Branching
also occurs in polymers. The branches are extensions of linked
monomer units that protrude from the polymer trunk chain. Branched poly-
mers can also form random coils, but the branches prevent a highly irregular
arrangement and, therefore, less crystallinity results because the molecules
cannot line up and pack as well.
means that the polymer molecules are interconnected by
some sort of bonding. The bonding can be covalent, ionic, or it can result
from intermolecular forces such as hydrogen bonding. With a small degree
of crosslinking, a loose network is obtained, such as in vulcanized rubber,
in which the crosslinks are formed by sulfur atoms. Highly crosslinked
polymers, such as a thermoset plastic, have such a rigid structure that when
heated they decompose or burn rather than melt. A crosslinked polymer is
one super giant molecule. For example, the polymer in a bowling ball is
literally one molecule.
Crosslinking
