Patent ID: 7619029

Claim:
A fiber composite material, comprising: an elastomer; carbon nanofibers having an average diameter of 0.7 to 15 nm and an average length of 0.5 to 100 micrometers; and fibers having an average diameter of 1 to 100 micrometers and an aspect ratio of 50 to 500, the carbon nanofibers and the fibers being dispersed in the elastomer, and the elastomer including an unsaturated bond or a group exhibiting affinity to the carbon nanofibers, wherein the fiber composite material includes the carbon nanofibers in an amount of 1 to 30 vol % and the fibers in an amount of 3 to 40 vol %, and has an average coefficient of linear expansion of 100 ppm (1/K) or less and a differential coefficient of linear expansion of 120 ppm (1/K) or less at −80 to 300° C.