Patent ID: 7927692

Claim:
A carbon fiber composite material comprising an elastomer and a plurality of carbon nanofibers substantially uniformly dispersed in the elastomer, wherein: the elastomer has an unsaturated bond or a group bonding with an active part of each carbon nanofibers; the elastomer in the composite material is in its uncrosslinked form; and the composite material has a first spin-spin relaxation time (T 2 n ) of 100 to 3,000 μsec and a second spin-spin relaxation time (T 2 nn ) of being absent or 1,000 to 10,000 μsec, and a fraction (fnn) of components having the second spin-spin relaxation time of less than 0.2, as measured under conditions of an observing nucleus of 1 H at 150° C. by the Hahn-echo method using pulsed NMR technique.