Thermosettable resin composition and fibrous substrate impregnated with same

Claim 1

AN IMPROVED THERMOSETTABLE COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF (A) A SUBSTANTIALLY HOMOGENEOUS INTERPOLYMER HAVING POLYMERIZED THEREIN (1) 20-45 MOL PERCENT OF AN ACID MONOMER SELECTED FROM THE GROUP CONSISTING OF AN ALPHA,BETA-ETHYLENICALLY UNSATURATED POLYBASIC ACID, AN ANHYDRIDE OF AN ALPHA,BETA-ETHYLENICALLY UNSATURATED POLYBASIC ACID AND MIXTURES THEREOF, AND (2) 80-55 MOL PERCENT OF AT LEAST ONE VINYLDENE MONOMER INTERPOLYMERIZABLE WITH SAID ACID MONOMER, SAID INTERPOLYMER HAVING SAID ACID MONOMER AND SAID VINYLIDENE MONOMER COMBINED THROUGHOUT THE POLYMER CHAINS IN ESSENTIALLY THE SAID MOL RATIOS THEY ARE POLYMERIZED THEREIN, AND (B) AN EPOXY COMPOUND CONTAINING A PLURALITY OF EPOXY GROUPS; SAID COMPONENTS (A) AND (B) BEING PRESENT IN A RATIO TO PROVIDE AN AVERAGE OF ABOUT 0.2-1.2 EPOXY GROUP PER CARBOXYL GROUP OF SAID COMPONENT (A); THE IMPROVEMENT COMPRISING IN ADMIXTURETHEREWITH 1-10 WEIGHT PERCENT OF SILICA AEROGEL BASED ON THE TOTAL WEIGHT OF THE RESIN SOLIDS.