Abstract: A hardener composition useful for curing epoxy resins including a blend of (a) a carboxylic anhydride which is a copolymer of an ethylenically unsaturated anhydride and a vinyl compound; (b) a copolymer of an ethylenically unsaturated anhydride and an elastomer; and optionally (c) a stabilizing agent such as a block copolymer to prevent phase separation of components (a) and (b). The hardener composition is particularly useful in electrical laminates applications.

Abstract: These crosslinked microparticles between 10-300 nm in size are obtained by dispersion polymerization, in non-aqueous medium which is non-solvent for the polymer formed, of a composition of ethylenically unsaturated polymerizable compounds, comprising: at least one monomer A, comprising only one ethylenic unsaturation, giving the microparticles formed in the said non-aqueous medium self-stabilization during and after polymerization, without any addition of polymer having the function of a stabilizing agent, tither before, during or after polymerization, at least one compound B comprising at least two ethylenic unsaturations and optionally, depending on the case: at least one compound C comprising only one ethylenic unsaturation and/or at least one compound D which is different from A, B and C and comprising at least one ethylenic unsaturation which can undergo radical-mediated polymerization and at least one second reactive function f1 which is other than an ethylenic unsaturation.