The present disclosure relates to an ultraviolet absorber, a preparation method therefor, and an ultraviolet screening product containing same and, more specifically, to: an ultraviolet absorber, which comprises polymeric carbon nitrides having a heterocyclic structure comprising C and N; a preparation method therefor; and an ultraviolet screening product containing same.

The present invention relates to novel compositions comprising cyanate ester resins and substituted bisimides (citraconimides, bisitaconimide, citraconimido-itaconimide, bisnadicimide, bistetrahydroimide and mixtures thereof) as defined in claim 1, and thermoset composite materials based on these compositions.

A stabilised aqueous formazin composition comprises 100 parts by weight water; up to 0.03 parts by weight formazin polymer; 0.4 to 5 parts by weight hexamethylenetetramine; and a buffer composition, wherein the buffer composition is adjusted to maintain a pH of the formazin solution in a range between 8.4 and 10. The stabilised formazin composition has a turbidity of 400 NTU or less. A diluent for preparing the stabilised formazin composition from a formazin stock composition is provided, wherein the diluent comprises hexamethylenetetramine in a concentration of between 4 and 50 g/l and a buffer composition adjusted to a pH of the diluent in a range of from 8.4 to 10.

The invention relates to a gelled aqueous polymer composition for forming, by means of drying then pyrolysis, a monolithic porous carbon, to a pyrolysed carbonated composition produced by the drying, followed by the pyrolysis, of said gelled composition, to a porous carbon electrode for a supercapacitor comprising said pyrolysed composition, and to methods for producing said respectively gelled and pyrolysed compositions. A gelled composition according to the invention, produced from the polycondensation of polyhydroxybenzene(s) and hexymethylenetetramine, is such that the hexymethylenetetramine comprised therein represents a mass fraction of between 7% and 15% inclusive. Said gelled composition is produced by a) polycondensation in an aqueous solvent of the polyhydroxybenzene(s) and hexymethylenetetramine, followed by b) gelling by heating of said polycondensate.

A gelled aqueous polymer composition made from a resin produced by polycondensation of at least: a polyhydroxybenzene R, preferably resorcinol, hexamethylenetetramine HMTA, an anionic polyelectrolyte PA, preferably phytic acid. An aerogel obtained by drying these microparticles, and porous carbon microspheres obtained from the gel microparticles by pyrolysis. A method for producing a polymerised aqueous gel, an aerogel and porous carbon microspheres. Electrodes and electrochemical cell prepared from the porous carbon particles.

A stabilised aqueous formazin composition comprises 100 parts by weight water; up to 0.03 parts by weight formazin polymer; 0.4 to 5 parts by weight hexamethylenetetramine; and a buffer composition, wherein the buffer composition is adjusted to maintain a pH of the formazin solution in a range between 8.4 and 10. The stabilised formazin composition has a turbidity of 400 NTU or less. A diluent for preparing the stabilised formazin composition from a formazin stock composition is provided, wherein the diluent comprises hexamethylenetetramine in a concentration of between 4 and 50 g/l and a buffer composition adjusted to a pH of the diluent in a range of from 8.4 to 10.

The present invention relates to novel compositions comprising cyanate ester resins and substituted bisimides (citraconimides, bisitaconimide, citraconimido-itaconimide, bisnadicimide, bistetrahydroimide and mixtures thereof) as defined in claim 1, and thermoset composite materials based on these compositions.

The invention relates to a gelled aqueous polymer composition for forming, by means of drying then pyrolysis, a monolithic porous carbon, to a pyrolysed carbonated composition produced by the drying, followed by the pyrolysis, of said gelled composition, to a porous carbon electrode for a supercapacitor comprising said pyrolysed composition, and to methods for producing said respectively gelled and pyrolysed compositions. A gelled composition according to the invention, produced from the polycondensation of polyhydroxybenzene(s) and hexymethylenetetramine, is such that the hexymethylenetetramine comprised therein represents a mass fraction of between 7% and 15% inclusive. Said gelled composition is produced by a) polycondensation in an aqueous solvent of the polyhydroxybenzene(s) and hexymethylenetetramine, followed by b) gelling by heating of said polycondensate.