A polyamide is a polymer in which the repeating unit in the chain contains the amide functional group.
Polyamides are thermoplastic polymers.
The main kinds are:
• polyamides 6 or polycaprolactams;
• polyamides 6-6 and 6-10;
• polyamides 11 and 12;
• aromatic polyamides more commonly called aramids.
Polyamides differ in the length of the linking units between the amide groups and the arrangement of these groups. Some properties are strongly affected by the length of the chains.
The general properties of polyamides are:
• good mechanical properties;
• dynamic fatigue and wear resistance;
• a low coefficient of friction;
• good behaviour to heat and cold and to a large number of chemicals;
• moderate price;
• sensitivity to and swelling with water;
• high shrinkage.