Thermoprocessable copolymers of TFE

Thermoprocessable copolymers of TFE consisiting essentially of the following monomers in the indicated amounts:

• A)
• (a) 8.6-9.8% by weight of perfluoromethylvinylether (FMVE);
• (b) 0.3-1.2% by weight of a perfluorodioxole of formula:
• 3
• wherein:
• Y═F, ORf, Rf wherein Rf is a perfluoroalkyl having from 1 to 5 carbon atoms;
• X1 and X2, equal to or different from each other, are —F or —CF3;
• with the proviso that the sum of the percentages by weight of (a)+(b) is from 8.9 to 11% by weight;
• or
• B)
• (a) 4.5-8.5% by weight of perfluoromethylvinylether (FMVE);
• (b) 1.7-7.5% by weight of a perfluorodioxole as defined in A);
• with the proviso that the sum of the percentages by weight of (a)+(b) is from 6.2 to 11% by weight;
• the complement to 100% by weight in compositions A) and B) being TFE;
• said copolymers having:
• an amount of ionic end groups —COOH and —COF, not higher than 5×10−4 moles/Kg polymer;
• release values of F− ions, determined on the polymer in pellet, not higher than 1 ppm by weight with respect to the polymer weight;
• wherein the manufactured articles obtained from the polymers having compositions A) or B) show the following mechanical properties:
• elongation at break≧130% measured at 23° C. along the welding lines of the injection moulded articles;
• stress at break≧2.5 MPa and elongation at break≧250%, measured at 250° C. on compression moulded plaque.