Foamable thermoplastic mixture, comprising at least one thermoplastic polymer selected from ethylene-vinyl acetate copolymer, ethylene methyl acrylate copolymer, ethylene butyl acrylate copolymer, ethylene-hexene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, polyethylene, polypropylene and ethylene-propylene copolymer, at least one long chain branched polymer with a g value, determined on the basis of high temperature GPC, as the ratio of the intrinsic viscosity of the polymer to be analyzed to the intrinsic viscosity of the PE-Standard NBS 1475 according to Kulin et al., Pure and Applied Chemistry 1988, 6,, p. 1403-1415, of less than 1 as a foam stabilizer selected from ethylene-vinyl acetate copolymer, ethylene methyl acrylate copolymer, ethylene butyl acrylate copolymer, ethylene-hexene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, polyethylene, polypropylene and ethylene-propylene copolymer and at least one chemical blowing agent, wherein the long chain branched polymer is present in an amount of 1 to 30 wt.% relative to the total weight of thermoplastic polymer and long chain branched polymer, and at least one of the following distinguishing features applies for the thermoplastic polymer and the long chain branched polymer: 1) the value of the melt flow index, determined at 190 °C and 2.16 kg according to ASTM D1238, of the long chain branched polymer (MFI) is smaller than the MFI value of the thermoplastic polymer (MFI), wherein MFI is a maximum of 50% of MFI, 2) the g value of the long chain branched polymer (g) is smaller than the g value of the thermoplastic polymer (g), wherein g is a maximum of 80% of g, 3) the polymer type of the long chain branched polymer differs from the polymer type of the thermoplastic polymer. at least one thermoplastic polymer selected from ethylene-vinyl acetate copolymer, ethylene methyl acrylate copolymer, ethylene butyl acrylate copolymer, ethylene-hexene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, polyethylene, polypropylene and ethylene-propylene copolymer, at least one long chain branched polymer with a g value, determined on the basis of high temperature GPC, as the ratio of the intrinsic viscosity of the polymer to be analyzed to the intrinsic viscosity of the PE-Standard NBS 1475 according to Kulin et al., Pure and Applied Chemistry 1988, 6,, p. 1403-1415, of less than 1 as a foam stabilizer selected from ethylene-vinyl acetate copolymer, ethylene methyl acrylate copolymer, ethylene butyl acrylate copolymer, ethylene-hexene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, polyethylene, polypropylene and ethylene-propylene copolymer and at least one chemical blowing agent, wherein the long chain branched polymer is present in an amount of 1 to 30 wt.% relative to the total weight of thermoplastic polymer and long chain branched polymer, and at least one of the following distinguishing features applies for the thermoplastic polymer and the long chain branched polymer: 1) the value of the melt flow index, determined at 190 °C and 2.16 kg according to ASTM D1238, of the long chain branched polymer (MFI) is smaller than the MFI value of the thermoplastic polymer (MFI), wherein MFI is a maximum of 50% of MFI, 2) the g value of the long chain branched polymer (g) is smaller than the g value of the thermoplastic polymer (g), wherein g is a maximum of 80% of g, 3) the polymer type of the long chain branched polymer differs from the polymer type of the thermoplastic polymer. 1) the value of the melt flow index, determined at 190 °C and 2.16 kg according to ASTM D1238, of the long chain branched polymer (MFI) is smaller than the MFI value of the thermoplastic polymer (MFI), wherein MFI is a maximum of 50% of MFI, 2) the g value of the long chain branched polymer (g) is smaller than the g value of the thermoplastic polymer (g), wherein g is a maximum of 80% of g, 3) the polymer type of the long chain branched polymer differs from the polymer type of the thermoplastic polymer.