Mixtures of aromatic polycarbonates and/or aromatic polyesters with special copolymers

Mixtures containing

• (I.) 10 to 98 parts by weight of thermoplastic aromatic polycarbonates or thermoplastic aromatic polyester or a mixture of both and
• (II.) 90 to 2 parts by weight of copolymers corresponding to formula (Ia)
• --A--X--B].sub.r (Ia)
• in which r is an integer of 1 to 20,
• --A-- represents polymers of cyclic carbonates corresponding to formula (v) ##STR12## or to formula (VI) ##STR13## or to formula (v) and (VI), --B-- represents polymers of lactones corresponding to formula (VII) ##STR14## and --X-- represents polymers containing at least one of the carbonates (V) or (VI) together with the lactones (VII) in polymerized form, the concentration of the polymerized carbonates (V) and (VI) decreasing continuously towards the blocks --B-- and the concentration of the polymerized lactones (VII) decreasing continuously towards the blocks --A-- ("tapered structure") and the sum of the parts by weight of components (I) and (II) amounting to 100 parts by weight;
• R.sup.1 in (V) is a linear C.sub.3 -C.sub.10 alkylene or a moiety corresponding to formulae (a) to (1)
• (a) --CH.sub.2 CH.sub.2 CH(CH.sub.3)--
• (b) --CH.sub.2 CH.sub.2 OCH.sub.2 CH.sub.2 OCH.sub.2 CH.sub.2 --,
• (c) --CH.sub.2 CH(CH.sub.3)CH.sub.2 CH.sub.2 C(CH.sub.3).sub.2 CH.sub.2 --, ##STR15## R.sup.2 in (VI) is a linear C.sub.4 -C.sub.12 alkylene or a moiety corresponding to formulae (m) or (b)
• (m) --CH.sub.2 --CH.sub.2 --O--CH.sub.2 --CH.sub.2 -- or
• (b) --CH.sub.2 --CH.sub.2 --O--CH.sub.2 --CH.sub.2 --O--CH.sub.2 --CH.sub.2 -- and
• R.sup.3, R.sup.4, R.sup.5 and R.sup.6 in (VII) are the same or different and each represents H, C.sub.1 -C.sub.6 alkyl, C.sub.3 -C.sub.6 alkylene, C.sub.1 -C.sub.6 alkoxy or C.sub.2 -C.sub.6 -alkyleneoxy-C.sub.1 -C.sub.6 -alkyl, and
• m and n in (VII) independently of one another are 0, 1, 2, 3, 4, 5 or 6.