Abstract: The invention relates to a star-shaped branched polyamide that has a high thermal stability and can be produced in existing production facilities for the corresponding linear polyamide. This is achieved by allowing the polyamide branches, at least three, to be formed from a multifunctional core having functional groups chosen from the group comprising amine and carboxyl groups, the amine or carboxyl groups being bound to an acyclic compound in which branching occures, if it is branched, at a carbon atom, or via an acyclic chain to a heterocyclic compound showing point symmetry.The process for the preparation is carried out under the conditions of the preparation of the corresponding linear polyamide. It proves to be possible to obtain, after shorter polymerization times, a product with mechanical properties that are comparable with those of the linear polyamide after significantly longer polymerization times.

Abstract: The invention relates to a polyamide fiber whose polyamide is heavily branched. The branched polyamide preferably has 3-20 branches which are joined to a core molecule which is smaller than the polyamide arms. The arms originate preferably from functional groups which are identical and are preferably carboxyl groups. The polyamide is chosen from the group of polyamides which are produced by polycondensation of .alpha.,.omega.-aminocarboxylic acids or by ring-opening polymerization of lactams. Preferably, the polyamide is nylon-6. The properties of the fiber according to the invention are at least at the same level as those of fibers obtained by spinning linear polyamide. The spinning process for the fiber according to the invention is less susceptible to faults. Inter alia, the viscosity of the polyamide no longer changes during the spinning process.