Abstract: Liquid reactive thermosetting compositions comprising:A) At least one polyepoxide or a mixture of one or more polyepoxides with at least one monoepoxide, of an aliphatic, cycloaliphatic or mixed nature;B) at least one anhydride of a di- or polycarboxylic acid of an aliphatic, cycloaliphatic or mixed nature;C) at least one catalyst capable of promoting the rapid polymerization of the mixture A+B under microwave irradiation and having general formula (I):N.tbd.C--CH.sub.2 --CH(Z)--(O).sub.r --Y.sup.+ NR.sub.1 R.sub.2 R.sub.3 X.sup.-.

Abstract: Crosslinkable liquid composition based on organic isocyanates and epoxy compounds, comprising the following components:(A) an organic polyisocyanate;(B) a polyepoxide or mixture of a polyepoxide and a monoepoxide; and(C) a catalyst constituted by at least one cyanoderivative containing a quaternary nitrogen atom,which composition can be polymerized at temperatures of 40.degree. C. or higher, by a process comprising exposure thereof to a non-ionizing electromagnetic radiation having a frequency comprised in the microwave range of frequencies, to obtain a solid material endowed with an excellent combination of physical, chemical and mechanical properties.