TECHNOLOGY FOCUS - POLYMERS - Preferred Polymers: The necessary radicals are formed (a) in a polymerisation process, (b) in a polymerisation process in the absence or presence of oxygen and without further stabilisation treatment for higher processing temperatures, or (c) by thermal degradation of the perfluoropolymer with or without further treatment with oxygen and without stabilisation treatment as above (followed by reaction with B in each case). The unsaturated groups may be in the main chain and/or in side chains. Component (A) comprises polytetrafluoroethylene (PTFE) and/or tetrafluoroethylene-hexafluorpropylene copolymer, preferably PTFE in the form of powder, especially micro-powder. Component (B) has at least one olefinically unsaturated group; suitable monomers comprise (meth)acrylic acid, (meth)acrylate esters, styrene, divinylbenzene, styrenesulfonic acid or trifluorovinylbenzenesulfonic acid or their salts, compounds of formula CF2=CF-O-(CF2CF(CF3)O)n-(CF2)m-SO2F or the corresponding sulfonic acid (in whichm = 1 or more, preferably 3;n = 0 or more, preferably 1), vinyl acetate, (meth)acrylonitrile, glycidyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide derivatives and/or maleic anhydride (as comonomer); suitable macromers are radically-coupled polyether-(meth)acrylates based on (co)polymers with ethylene glycol, propylene glycol and/or butylene glycol units; suitable oligomers and/or polymers comprise radically-coupled SBS, ABS, SBR, NBR, NR and other homo-, co- or ter-polymers of butadiene and/or isoprene and/or chloroprene (such polymers have unsaturated groups in the main chain and/or in side chains). Perfluorinated monomers with functional groups may also be radically coupled to the perfluoropolymer chains of an oligo-/poly-TFE arising from polymerisation or thermal degradation. A grafting reaction may be carried out on the (block)-copolymer product directly after polymerisation of the perfluoropolymer or later, or after thermal degradation, in the main reactor or a separate reactor. Other monomers, macromers, oligomers and/or polymers with or without functional groups may be coupled to (I) by reactive conversion. EXAMPLE - A mixture of 450 ml water, 60 mg sodium bisulfite, 2 mg iron(II) sulfate heptahydrate and 125 mg ammonium perdisulfate was pressurised to 0.3 MPa with a 5:1 mixture of tetrafluoroethylene (TFE) and hexafluoropropene (HEP, polymerised for 30 minutes at the same pressure, treated with argon (0.2 MPa) containing 0.5 vol% oxygen, stirred for 5 minutes, evacuated, treated with more TFE/HEP mixture (0.3 MPa) and polymerised for a further 30 minutes. This operation was repeated until a suspension (FEP(2)asterisk) was obtained. A dispersion of 25 g solid FEP(2)asterisk (from the above suspension) in 150 ml DMAc was heated to 100degreesC, treated with 50 ml glycidyl methacrylate (GMA), stirred for 2 hours at 120degreesC and worked up by filtration followed by washing with acetone and methanol. IR analysis showed that the product was a graft copolymer of GMA on the FEP copolymer. Molten polyamide 6.6 (45 g) was treated in a kneader at 260degreesC with 10 g graft copolymer and then mixed for a further 5 minutes. The mixture was worked up by treatment with formic acid followed by centrifuging (repeated 5 times), after which the solid was washed with methanol and dried. IR analysis showed the presence of FEP and non-removable polyamide. A compression-moulded block of the product showed very smooth sliding properties, with a coefficient of friction of 0.15, compared with 0.5-0.6 for pure polyamide; in abrasion tests, the product showed 80% less wear than pure polyamide.