PA is a semi-crystalline polymer.
There are two types: those made of one basic material (e.g. PA 6) and those made of two basic materials (e.g. PA 66). They can occur both naturally (e.g. wool and silk) and synthetically (e.g. nylon).
Polyamides have excellent mechanical properties and can be either hard and tough or soft and flexible. They absorb moisture and have excellent slide and wear characteristics. Polyamides are commonly used in the textile and automotive industry.