The invention relates to thermoplastic moulded masses comprising the components A) at least one thermoplastic polyamide, B) at least one hyper-branched polyetheramine, C) at least one amorphic oxide and/or oxide hydrate of at least one metal or semi-metal having a weighted average diameter of the primary particles of 0,5 to 20 nm. The invention also relates to the use of known components B) and C) for improving the flowability and/or thermal stability of polyamides, to the use of moulded masses for producing fibres, films and moulded bodies of all types and to the thus obtained fibres, films and moulded bodies.