Abstract: A filter element for adsorbing gaseous components of a gas stream comprises a fabric formed from fibres of a polymeric material in which the sizes of individual fibres is not more than about 20 &mgr;m. The fibres are treated by a copolymerisation reaction with a vinyl monomer which is capable of reacting with an acid or a base to form a salt directly or indirectly under conditions which result in grafting of the vinyl monomer to the surfaces of the fibres.

Abstract: A polymeric sheet, which is particularly suited for use as a separator in an electrochemical device, is formed by graft copolymerising acrylic acid, or another vinyl monomer capable of reacting with an acid or a base to form a salt directly or indirectly with fibers of a non-woven sheet, whose outer surface is provided by a polyolefin, especially polypropylene. The polyolefin is crosslinked as a result of the polymerisation reaction. The polymerisation reaction is preferably initiated by exposure of the sheet to ultraviolet radiation, after impregnation with an appropriate solution of the vinyl monomer.

Abstract: A polymeric sheet, which is particularly suited for use as a separator in an electrochemical device, is formed by graft copolymerizing acrylic acid, or another vinyl monomer capable of reacting with an acid or a base to form a salt directly or indirectly with fibers of a non-woven sheet, whose outer surface is provided by a polyolefin, especially polypropylene. The polyolefin is crosslinked as a result of the polymerization reaction. The polymerization reaction is preferably initiated by exposure of the sheet to ultraviolet radiation, after impregnation with an appropriate solution of the vinyl monomer.