Merylithe

Jacques Ferrand

Jean-Pierre Pascault

Francoise Mechin

Stéphanie Lambour

The invention concerns a thermosetting elastomer composition based on modified polycyanurate with improved thermal resistance obtainable by a polymerization method in the presence of a catalyst (D) of a mixture comprising at least: (A) a cyanate, (B) a block copolymer consisting of: a) at least a central block (B1) non-miscible with the cyanate and sufficiently long to provide the composition with elastomeric character; and b) at least two terminal blocks (B2) located on each side of the central block and comprising groups reactive with the cyanate, each of the blocks (B2) being sufficiently long to be miscible with the cyanate; and (C) a mineral filler reactive with the cyanate, in proportions such that the ratio r is not less than 5, but remains less than a threshold value to avoid phase inversion, said method comprising steps which consist in: I) mixing (A), (B), (C) and (D) until a homogeneous mixture is obtained at a temperature higher than the melting point of (A) and of (B) but lower than about 130&#xb0; C.; II) polymerizing the mixture at a temperature ranging between about 130 and about 170&#xb0; C.; III) post-curing the polymerized mixture at a temperature not lower than about 200&#xb0; C. to complete the reaction; the values of dsrupt and of derupt of the resulting composition being not more than +&#x2212;30%. The invention also concerns the method for preparing said composition and its use.

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Briarres sur Essonne, France

Jacques Ferrand