Abstract: A linear block copolymer of regular structure, comprising polyamide and polyethylene glycol blocks. Two polyamide blocks (A) are bound through an intermediate polyethylene glycol block (B) according to a structural scheme (A-B-A). Fibers exhibiting a high moisture absorption strong mechanical properties and a high dyeability. Textile manufactured goods comprising said fibers. A process to obtain said block copolymer, through the preparation of a polyamide (A) and a polyethylene glycol (B), and condensation of polyamide (A) and polyethylene glycol (B) so as to obtain a (A-B-A) structure.

Abstract: The invention is concerned with a combination of molecular weight controllers to be used in the production of a stabilized polyamide having a low content of monomers and oligomers and a high dye-taking capability by polymerization of caprolactam. The combination comprises: (a) a primary monofunctional amine having its boiling point at 180.degree. C. above, and a basic dissociation constant K.sub.b .gtoreq.1.7.times.10.sup.-5 ; (b) a monofunctional organic acid having a K.sub.a >1.5.times.10.sup.-5 ; and (c) an aminoacid containing at least ten carbon atoms having the --NH.sub.2 group salified by a monofunctional organic or inorganic acid which has K.sub.a >1.0.times.10.sup.-2. With this combination, a polyamide is obtained which, following residence in the molten state, has a monomer content of 0.25% or less and a dimer content of 0.15% or less.