Polymer Technology

Polyamides are polymers that contain an amide group, -CONH-, as a recurring part of the chain. Synthesis of polyhexamethylene adipamide, the original “nylon”, in the DuPont laboratory in 1935 provided a material whose properties were appropriate for apparel use and resulted in its commercial introduction in 1938 The other principal polyamide or nylon, polycaprolactum, was made in an 18 Farben laboratory by Schlack in 1938.

Although use as fiber dominated the interest in nylon, application as plastic for variety of purposes such as brush filaments, wire coating, coil forms, and gears occurred very soon thereafter. The use of nylons as plastics has increased steadily against that of fiber.

Nomenclature

The nylons (polyamides) are most often made from diamines and dibasic acids(1), D)-amana acids(2), or ladums(3).

The polyamides (PA) or nylons are identified by numbers corresponding to the number of carbon atoms in the monomers (diamine first).

For example for the nylons showed in (1):

Nylon 46 or PA 46 is polymerized from
H2N(CH2)4NH2 and HOOC(CH2)4COOH

Nylon 66 or PA 66 is polymerized from
H2N(CH2)6NH2 and HOOC(CH2)4COOH

Nylon 612 or PA 612 is polymerized from
H2N(CH2)6NH2 and HOOC(CH2)lOCOOH

And for the nylons showed in (2 and 3)
Nylon 6 or PA 6 is polymerized from H2N(CH2)5COOH
Nylon 12 or P A 12 is polymerized from H2N(CH2)11COOH

Polyamides are prepared in a similar way to polyesters but with amine functional groups replacing the hydroxyl functional groups.

For example, Nylon 6.10 (a polyamine) is prepared as follows