Polyamides, Fibers

Abstract

Polyamide fibers are spun from linear thermoplastic polymers having recurring amide groups made from diamines and dicarboxylic acids (CONH R NHCO R ) n or lactams (RCONH) n . Polyamides are generally referred to as nylons when R and R are essentially aliphatic, alicyclic, and less than 85% of the amide linkages are attached directly to two aromatic rings. When these linkages are equal to or greater than 85% aromatic, the fibers are referred to as aramids. Polyamides from the condensation of diamines and dicarboxylic acids are termed AABB type, and those from lactams, AB type. Aliphatic polyamides are identified by numerals that indicate the number of carbon atoms in the monomer. One number is used for the AB type and two numbers, the first designating the diamine, for the AABB type. For example, the polyamide made from caprolactam (six carbons) is nylon-6 [25038-54-4], and those from hexamethylenediamine and adipic acid, nylon-6,6 [9011-56-6]. Monomers containing ring structures are coded by either a single letter such as T for terephthalic acid (nylon-6,T) or an abbreviated form such as PACM for bis(p-aminocyclohexyl)methane, eg, PACM-12. In designating a random copolyamide, the components are named in order of decreasing percentages, followed by their weight percentages in parentheses. For example, if hexamethylenediamine adipic acid, sebacic acid, and dodecanedioic acid are copolymerized to give 50% nylon-6,6, 40% nylon-6,10, and 10% nylon-6,12, the product can be designated as nylon-6,6/6,10/6,12 (50/40/10). A block copolyamide, which is made by melt-blending two polyamides or a yarn consisting of fibers spun from two different polymer melt streams such as nylon-6,6 and nylon-6,10, can be designated as nylon-6,6//6,10 (50//50).Wallace H. Carothers and his research team at DuPont discovered nylon-6,6, which is covered in his patents issued in 1937 and 1938. Diamines from C 2 to C 18 were synthesized and reacted with aliphatic and aromatic dicarboxylic acids to make polyamides, which were then melt spun and evaluated as fibers. Nylon-6,6 was ultimately selected for scale-up and development because of its favorable

Melt-Spun Fibers for Textile Applications

“…Globally, PA 6 and PA 6.6 are by far the most used polyamides that are also significant for large-scale production of melt-spun fibers [ 29 ]. PA 6.6 is produced by the condensation reaction of hexamethylenediamine and adipic acid, while PA 6 is synthesized by ring-opening polymerization of ε-caprolactam [ 30 ].…”

Nitrogen‐Containing Polymers Derived from Terpenes: Possibilities and Limitations

“…They further represent the two pathways that can be used for polyamide synthesis, as PA‐6,6 is produced by a polycondensation reaction between adipic acid and 1,6‐hexanediamine, while PA‐6 is obtained by the ring‐opening polymerization (ROP) of ε ‐caprolactam. [ 3 ] Polyamide properties differ and can be adjusted depending on the nature of the monomers employed for their synthesis. Moreover, common remarkable features can be defined due to the common amide linkage of the repeating unit.…”