Abstract: A thermoset material obtained from a curing by heat treatment of a resin that can be obtained by polycondensation, in basic medium, of at least one phthalonitrile compound bearing on its benzene ring at least one hydroxyl group.

Abstract: A method for preparing a resol-type phenolic resin comprising the following steps: a) a step of condensing phenol and formaldehyde, in a basic medium, the formaldehyde being in molar excess with respect to the phenol, at a condensation temperature of at least 50° C. until the phenol conversion rate is 50 to 80%, whereby a resol-type phenolic resin results comprising free formaldehyde; b) a step of measuring the free formaldehyde content of the phenolic resin obtained in a); c) a step of reducing the free formaldehyde content of the phenolic resin obtained in a) by placing it in contact with an aminophenolic compound in an excess amount with respect to the free formaldehyde and at a temperature lower than the condensation temperature of step a).