A process for making a fluent blend of an advanced epoxy resin and an extender polymer, said epoxy resin and said extender polymer each having aliphatic backbone carbon atoms that have either one or two carbon atoms bonded thereto, which comprises:
- mixing an aromatic 1,2-epoxy resin, having an epoxy equivalent weight below about 2,000, with at least one extender polymer and with a sufficient amount of an organic solvent to render the mixture fluent, and then
- advancing the epoxy resin in the presence of said extender polymer and said solvent, by reacting the epoxy resin with a polyfunctional compound that adds to the epoxy resin at its epoxide groups, to increase the molecular weight of the resin, which polyfunctional compound is either a polycarboxylic compound or a polyhydroxy compound,
- maintaining sufficient solvent in the mixture that the blend of advanced epoxy resin and extender polymer remains fluent, and
- polymerizing addition polymerizable monomer in the presence of said mixture by addition polymerization under addition polymerizing conditions.