Polymer

A polymer is a molecule of high molecular mass made up of monomers linked together by covalent bonds, for example starch and proteins.

Generally, an organic or semi-organic substance with one or more types of repeating monomer units.

Thermoplastic, thermosetting and elastomer materials are polymers. Polymer matrices are much used in composite materials.

Organic fibres (Aramid) are made up of linear polymers; carbon fibres and some silicon carbide fibres are manufactured from organic precursors.

The properties of polymers depend on:

• the way the monomers are assembled;
• the degree of polymerisation.

There are:

• homopolymers (linear, ramified, stereoregular); these are polymers made up of an association of molecules from a single monomer unit; the chain is linear;

• copolymers, with the polymerisation of two or more different monomers;

• cross linked polymers, where the macromolecules are linked over the three directions in space (cross linked macromolecules).