Homogeneous polyepoxide-polyanhydride compositions

A handleable, thermosettable composition which comprises a homogeneous resin mixture of polyanhydride molecules, polyepoxide molecules of an epoxy resin having a 1,2-epoxy equivalent value greater than 1, a saturated monoanhydride, a monoepoxy compound, and from about 0.01 to about 10 weight percent of an anhydride accelerator,

• said polyanhydride comprising the addition copolymer of (1) styrene and (2) maleic anhydride in a molar ratio of styrene (1) to maleic anhydride (2) of about 0.5:1 to about 8:1 and (3) a styrene-maleic anhydride copolymer having between two and about 500 repeating units and a styrene to maleic anhydride ratio between about 1:1 and about 10:1;
• said saturated monoanhydride selected from phthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, chlorendic anhydride and a mixture of methyl bicyclo(2.2.1)heptane-2,3-dicarboxylic anhydride isomers;
• the ratio of anhydride equivalents derived from said maleic anhydride (2) to the total sum of the anhydride equivalents in said homogeneous resin mixture being between about 0.2:1 and about 1:1 and the ratio of anhydride equivalents in said saturated monoanhydride to the anhydride equivalents derived from said styrene-maleic anhydride copolymer (3) being between zero and about 1:1;
• the A/E ratio of total anhydride equivalents to total epoxy equivalents in said composition being between about 0.1:1 to about 2.5:1 and the ratio of epoxy equivalents in the epoxy resin to the epoxy equivalents in the monoepoxy compound being at least about 1:1;
• and
• said handleable, thermosettable composition being substantially free of any volatile component.