Thermoprocessable copolymers of tetrafluoroethylene

Thermoprocessable tetrafluoroethylene copolymers, which consist of:

• (a) from 0.5 to 13% by weight of perfluoromethylvinylether;
• (b) from 0.05 to 3% by weight of one or more fluorinated monomers selected from the group consisting of:
• (1)
• R.sup.1 O-CF=CF.sub.2 (I)
• wherein R.sup.1 is selected from:
• i) --R.sub.F --T wherein R.sub.F is a perfluoroalkylene radical having from 2 to 12 carbon atoms and T is F, Cl or H;
• ii) ##STR7## wherein n is a number from 1 to 4, and m is a number from 0 to 3;
• iii) ##STR8## wherein the ##STR9## units are randomly distributed along the chain;
• X and Y are, independently from each other, --F or --CF.sub.3 ;
• Z is --(CFX)-- or --(CF.sub.2 --CFY)--;
• p and q, equal or different from each other, are numbers from 0 to 10;
• the average number molecular weight of the monomer being from 200 to 2,000;
• iv) ##STR10## wherein W is --Cl, --F or --CF.sub.3, and 1 and t are numbers from 0 to 5;
• ##STR11## wherein r is a number from 0 to 4;
• (2)
• R.sup.2 -CH=CH.sup.2 (VI)
• wherein R.sup.2 is a --R.sub.F --T group where R.sub.F is a perfluoroalkylene radical having from 2 to 12 carbon atoms, and T is F, Cl or H;
• c) tetrafluoroethylene, in such an amount that the sum of the percentages of the various monomers is equal to 100% by weight.