Composition containing (a) at least one polymeric aromatic carbodiimide of formula R 1 -R 2 -(-N=C=N-R 2 -) m -R 1, in which m represents an integer from 2 to 500, preferably 3 to 20, very particularly preferably 4 to 10, R 2 = C 1 -C 12 -alkyl-substituted arylenes, C 7 -C 18 -alkylaryl-substituted arylenes and also arylene, and R 1 = -NCO, -NCNR 3, -NHCONHR 3, -NHCONR 3 R 4 or -NHCOOR 5, wherein R 3 and R 4 are identical or different and represent a C 1 -C 12 -alkyl, C 6 -C 12 -cycloalkyl, C 7 -C 18 -aralkyl or aryl radical and R 5 represents a C 1 -C 22 -alkyl, C 6 -C 12 -cycloalkyl, C 6 -C18-aryl or C 7 -C 18 -aralkyl radical and an unsaturated alkyl radical having 2 - 22 carbon atoms or an alkoxypolyoxyalkylene radical, (b) at least one epoxide of formula where a is 0 to 10, preferably where a is 1 to 8, particularly preferably where a is 1 to 6, very particularly preferably in the range from 2 to 3, wherein a represents the average number and/or of formula where R 9, R 10 = H, C 1 -C 8 -alkyl, R 10 = C 1 -C 8 -alkyl, x, y = 1 - 20 and z = 2 - 20, and R* = H, C 1 -C 8 -alkyl, (c) at least one thermoplastic polyester-based polymer selected from the group polyethylene terephthalate, polytrimethylene terephthalate, thermoplastic polyester elastomers (TPE E), ethylene vinyl acetate, polylactic acid and/or PLA derivatives, polybutylene succinates, polyhydroxyalkanoates, and various blends, thermoplastic polyurethanes, polyurethane elastomers, PU adhesives and PU casting resins. (a) at least one polymeric aromatic carbodiimide of formula R 1 -R 2 -(-N=C=N-R 2 -) m -R 1, in which m represents an integer from 2 to 500, preferably 3 to 20, very particularly preferably 4 to 10, R 2 = C 1 -C 12 -alkyl-substituted arylenes, C 7 -C 18 -alkylaryl-substituted arylenes and also arylene, and R 1 = -NCO, -NCNR 3, -NHCONHR 3, -NHCONR 3 R 4 or -NHCOOR 5, wherein R 3 and R 4 are identical or different and represent a C 1 -C 12 -alkyl, C 6 -C 12 -cycloalkyl, C 7 -C 18 -aralkyl or aryl radical and R 5 represents a C 1 -C 22 -alkyl, C 6 -C 12 -cycloalkyl, C 6 -C18-aryl or C 7 -C 18 -aralkyl radical and an unsaturated alkyl radical having 2 - 22 carbon atoms or an alkoxypolyoxyalkylene radical, m represents an integer from 2 to 500, preferably 3 to 20, very particularly preferably 4 to 10, R 2 = C 1 -C 12 -alkyl-substituted arylenes, C 7 -C 18 -alkylaryl-substituted arylenes and also arylene, and R 1 = -NCO, -NCNR 3, -NHCONHR 3, -NHCONR 3 R 4 or -NHCOOR 5, wherein R 3 and R 4 are identical or different and represent a C 1 -C 12 -alkyl, C 6 -C 12 -cycloalkyl, C 7 -C 18 -aralkyl or aryl radical and R 5 represents a C 1 -C 22 -alkyl, C 6 -C 12 -cycloalkyl, C 6 -C18-aryl or C 7 -C 18 -aralkyl radical and an unsaturated alkyl radical having 2 - 22 carbon atoms or an alkoxypolyoxyalkylene radical, (b) at least one epoxide of formula where a is 0 to 10, preferably where a is 1 to 8, particularly preferably where a is 1 to 6, very particularly preferably in the range from 2 to 3, wherein a represents the average number and/or of formula where R 9, R 10 = H, C 1 -C 8 -alkyl, R 10 = C 1 -C 8 -alkyl, x, y = 1 - 20 and z = 2 - 20, and R* = H, C 1 -C 8 -alkyl, where R 9, R 10 = H, C 1 -C 8 -alkyl, R 10 = C 1 -C 8 -alkyl, x, y = 1 - 20 and z = 2 - 20, and R* = H, C 1 -C 8 -alkyl, (c) at least one thermoplastic polyester-based polymer selected from the group polyethylene terephthalate, polytrimethylene terephthalate, thermoplastic polyester elastomers (TPE E), ethylene vinyl acetate, polylactic acid and/or PLA derivatives, polybutylene succinates, polyhydroxyalkanoates, and various blends, thermoplastic polyurethanes, polyurethane elastomers, PU adhesives and PU casting resins.