Examples of aliphatic polyamides are PA6, PA66, PA11, PA12. Polyamide PA6 is synthesized by ring opening polymerization of caprolactam. PA66 is synthesized by polycondensation of adipic acid and hexamethylenediamine. PA11 is a bio-based, high performance polyamide produced from renewable castor seeds. PA12 is produced by ring-opening polymerization of laurolactam