The invention provides a molded article containing a specific fluororesin and having excellent hydrophilicity. The molded article containing the fluororesin has a melt flow rate of 1.00 g/10 min or lower and a water contact angle of 90° or smaller. The fluororesin contains at least one copolymer selected from the group consisting of a copolymer containing a tetrafluoroethylene unit and a perfluoro(alkylvinylether) unit and a copolymer containing a tetrafluoroethylene unit and a hexafluoropropylene unit.

A polymer optical fibre (POF) (30) for transmitting light of wavelength, λi, between two separate elements of an active implantable medical device (AIMD), includes a core (31) which is cylindrical and made of a cyclic olefin polymer (COP) or copolymer (COC), having a core refractive index at the wavelength, λi, n_core, A cladding (32) which has a cladding refractive index at the wavelength, λi, n_clad<n_core, and which is made of a cladding copolymer including monomers of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride. The cladding being itself enclosed in a coating (33) which is made of a coating polymer formed of one of the monomers of the cladding copolymer. The POF has a numerical aperture, NA, at the wavelength, λi, of at least 0.5.

A polymer optical fibre (POF) (30) for transmitting light of wavelength, λi, between two separate elements of an active implantable medical device (AIMD), includes a core (31) which is cylindrical and made of a cyclic olefin polymer (COP) or copolymer (COC), having a core refractive index at the wavelength, λi, n_core, A cladding (32) which has a cladding refractive index at the wavelength, λi, n_clad<n_core, and which is made of a cladding copolymer including monomers of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride. The cladding being itself enclosed in a coating (33) which is made of a coating polymer formed of one of the monomers of the cladding copolymer. The POF has a numerical aperture, NA, at the wavelength, λi, of at least 0.5.

A polymer optical fibre (POF) (30) for transmitting light of wavelength, λi, between two separate elements of an active implantable medical device (AIMD), includes a core (31) which is cylindrical and made of a cyclic olefin polymer (COP) or copolymer (COC), having a core refractive index at the wavelength, λi, n_core, A cladding (32) which has a cladding refractive index at the wavelength, λi, n_clad<n_core, and which is made of a cladding copolymer including monomers of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride. The cladding being itself enclosed in a coating (33) which is made of a coating polymer formed of one of the monomers of the cladding copolymer. The POF has a numerical aperture, NA, at the wavelength, λi, of at least 0.5.

The composition can include a fluoropolymer and a branched silsesquioxane polymer having terminal —Si(R.sup.3).sub.3 groups and units having formula, in which * represents a bond to another silicon atom in the branched silsesquioxane polymer, R is an organic group comprising an aliphatic carbon-carbon double bond, and R.sup.3 is a non-hydrolyzable group or hydrogen. The fluoropolymer can be crosslinked with the branched silsesquioxane polymer. An article can include a first composition including a fluoropolymer in contact with a second composition including a silicone, wherein at least one of the first composition or second composition includes the branched silsesquioxane polymer. At least one of the fluoropolymer or the silicone can be crosslinked with a branched silsesquioxane polymer including terminal —Si(R.sup.3).sub.3 groups and units having formula, in which R* is an organic group comprising a carbon-carbon bond between the branched silsesquioxane polymer and the fluoropolymer, the silicone, or another R* group.

The composition can include a fluoropolymer and a branched silsesquioxane polymer having terminal —Si(R.sup.3).sub.3 groups and units having formula, in which * represents a bond to another silicon atom in the branched silsesquioxane polymer, R is an organic group comprising an aliphatic carbon-carbon double bond, and R.sup.3 is a non-hydrolyzable group or hydrogen. The fluoropolymer can be crosslinked with the branched silsesquioxane polymer. An article can include a first composition including a fluoropolymer in contact with a second composition including a silicone, wherein at least one of the first composition or second composition includes the branched silsesquioxane polymer. At least one of the fluoropolymer or the silicone can be crosslinked with a branched silsesquioxane polymer including terminal —Si(R.sup.3).sub.3 groups and units having formula, in which R* is an organic group comprising a carbon-carbon bond between the branched silsesquioxane polymer and the fluoropolymer, the silicone, or another R* group.

A sealing member includes a thermoplastic fluororesin composition including a thermoplastic fluororesin (A) having a Shore D hardness of less than or equal to 50, the Shore D hardness being measured at 23° C. in accordance with ASTM D2240, and a cross-linked structure forming agent (B) that is selected from the group consisting of a polyfunctional unsaturated compound (b-1), a polyamine compound (b-2), and a polyhydroxy compound (b-3) and that is capable of forming a cross-linked structure through a reaction with the thermoplastic fluororesin (A), the thermoplastic fluororesin composition not substantially containing a peroxide compound when containing the (b-1), not substantially containing an acid acceptor when containing the (b-2), and not substantially containing at least one of the acid acceptor and an onium compound when containing the (b-3); and a method for producing a cross-linked body including a step of cross-linking the thermoplastic fluororesin composition by an ionizing radiation.

A sealing member includes a thermoplastic fluororesin composition including a thermoplastic fluororesin (A) having a Shore D hardness of less than or equal to 50, the Shore D hardness being measured at 23° C. in accordance with ASTM D2240, and a cross-linked structure forming agent (B) that is selected from the group consisting of a polyfunctional unsaturated compound (b-1), a polyamine compound (b-2), and a polyhydroxy compound (b-3) and that is capable of forming a cross-linked structure through a reaction with the thermoplastic fluororesin (A), the thermoplastic fluororesin composition not substantially containing a peroxide compound when containing the (b-1), not substantially containing an acid acceptor when containing the (b-2), and not substantially containing at least one of the acid acceptor and an onium compound when containing the (b-3); and a method for producing a cross-linked body including a step of cross-linking the thermoplastic fluororesin composition by an ionizing radiation.

A cross-linkable composition includes an elastomeric fluoropolymer and a semi-crystalline fluoroplastic. The composition enables manufacturing of articles which maintain favorable mechanical properties (e.g. tensile strength, elongation and flexibility) when continuously exposed to extreme temperatures. In addition, a cross-linked product obtained by subjecting said composition to ionizing radiation is disclosed, which may be used in heat-shrinkable articles, cable jackets and sealing elements.

A cross-linkable composition includes an elastomeric fluoropolymer and a semi-crystalline fluoroplastic. The composition enables manufacturing of articles which maintain favorable mechanical properties (e.g. tensile strength, elongation and flexibility) when continuously exposed to extreme temperatures. In addition, a cross-linked product obtained by subjecting said composition to ionizing radiation is disclosed, which may be used in heat-shrinkable articles, cable jackets and sealing elements.