Main Difference
The main difference between Polyimide and Polyamide is that the Polyimide is a polymer of imide monomers and Polyamide is a macromolecule with repeating units linked by amide bonds.
Polyimide
Polyimide (sometimes abbreviated PI) is a polymer of imide monomers. Polyimides have been in mass production since 1955. With their high heat-resistance, polyimides enjoy diverse applications in roles demanding rugged organic materials, e.g. high temperature fuel cells, displays, and various military roles. A classic polyimide is Kapton, which is produced by condensation of pyromellitic dianhydride and 4,4′-oxydianiline.
Polyamide
A polyamide is a macromolecule with repeating units linked by amide bonds.
Polyamides occur both naturally and artificially. Examples of naturally occurring polyamides are proteins, such as wool and silk. Artificially made polyamides can be made through step-growth polymerization or solid-phase synthesis yielding materials such as nylons, aramids, and sodium poly(aspartate). Synthetic polyamides are commonly used in textiles, automotive applications, carpets and sportswear due to their high durability and strength. The transportation manufacturing industry is the major consumer, accounting for 35% of polyamide (PA) consumption.
Polyimide (noun)
Any polymer whose monomers are imides; used to make high-temperature resins
Polyamide (noun)
Any of a range of polymers containing amide (or peptide) repeat units; examples include proteins and nylon.
Polyimide (noun)
a synthetic resin in which the polymer units are linked by imide groups, used chiefly for heat-resistant films and coatings.
Polyamide (noun)
a synthetic polymer of a type made by the linkage of an amino group of one molecule and a carboxylic acid group of another, including many synthetic fibres such as nylon.