A composition comprises a copolymer made from a thiol terminated hydrocarbon monomer and at least one additional monomer chosen from the compounds of i) a terminally unsaturated hydrocarbon monomer, ii) an isocyanate functionalized hydrocarbon monomer and iii) a silane monomer substituted with two or more C2 to C8 terminally unsaturated alkenyl groups or C2 to C8 terminally unsaturated alkynyl groups. The composition also includes a particulate filler dispersed in the copolymer and a solvent. If the terminally unsaturated hydrocarbon monomer is polybutadiene, the polybutadiene contains from about 0 mol % to about 30 mol % of polymer units in a cis-1,4-butadiene form. Composites made from the composition and methods for making composite panels are also disclosed.