Anionic polymerization has not achieved significant commercial application in the production of synthetic polyamide fibers because of the speed of the polymerization and the effects of minor impurities upon the molecular weights and molecular-weight distribution.
Because of the instability of these polymers, extremely large and variable viscosity changes occur when they are melt spun into a fiber One means of in the formation of mixed polyamides whose molecules contain diearboxylie acid. diamine, and a-amino acid residues . The reaction proceeds according to equation
5. When a diol is used, the resulting polyamide contains both amide and ester groups (structure (1). Other methods of polymerization are discussed in Ref. 103.