Composition copolymeric ethylene / tetrafluoroethylene.

A copolymer composition of ethylene / tetrafluoroethylene (C) having a melt viscosity of 100 to 350 Paus and tensile elongation of 250 450%; and comprising an ethylene / tetrafluoroethylene copolymer (A) having a melt viscosity of 80 to 300 Paus and an ethylene / tetrafluoroethylene copolymer (B) having a melt viscosity of 1,000 to 7,000 Paus in a mass ratio of (a) / (B) = 60/40 to 97/3; measuring the tensile elongation according to ASTM D3159 of; and measuring the melt viscosity as follows: an orifice having a diameter of 1 mm and a length of 10 mm on a capillary rheometer "Capirograph" manufactured by Toyo Seiki Seisaku-sho, Ltd. engages and extrudes an ethylene / tetrafluoroethylene molten under such conditions that the cylinder temperature is 240 ° C and the piston speed is 10 mm / min, whereby the melt viscosity is measured.