Carbon fiber composite material

1. A carbon fiber composite material having an elastomer and vapor-grown carbon fibers dispersed in the elastomer,

the vapor-grown carbon fibers being rigid fibers having an average diameter of 20 to 200 nm, an average length of 5 to 20 micrometers, and an average value of bending indices defined by the following expression (1) of 5 to 15,

Bending index= Lx÷D   (1)

Lx: length of linear portion of the vapor-grown carbon fiber, and

D: diameter of the vapor-grown carbon fiber, and

the carbon fiber composite material having a dynamic modulus of elasticity (E′) at 150° C. of 30 MPa or more and an elongation at break (EB) of 140% or more,

wherein an amount of the vapor-grown carbon fibers in the carbon fiber composite material is 15 to 60 wt %.

2. The carbon fiber composite material as defined in claim 1 ,

wherein the elastomer has a molecular weight of 5000 to 5,000,000; and

wherein a network component of the elastomer in an uncrosslinked form has a spin-spin relaxation time (T 2 n ), measured at 30° C. by a Hahn-echo method using a pulsed nuclear magnetic resonance (NMR) technique, of 100 to 3000 microseconds.

3. The carbon fiber composite material as defined in claim 1 ,

wherein the dynamic modulus of elasticity (E′) of a sheet of the carbon fiber composite material extruded from a mixer in a first direction includes a first dynamic modulus of elasticity (E′(L)) in the first direction and a second dynamic modulus of elasticity (E′(T)) in a direction which is perpendicular to the first direction and is a width direction of the carbon fiber composite material; and

wherein an orientation ratio (E′(L)/E′(T)) of the first dynamic modulus of elasticity (E′(L)) to the second dynamic modulus of elasticity (E′(T)) is 2 or less.

4. A carbon fiber composite material having an elastomer and vapor-grown carbon fibers dispersed in the elastomer,

the vapor-grown carbon fibers having an average diameter of 20 to 200 nm and an average length of 5 to 20 micrometers,

a change rate of a spin-lattice relaxation time (T 1 ′) of the carbon fiber composite material with respect to a spin-lattice relaxation time (T 1 ) of the elastomer, measured at 150° C. by an inversion recovery method using a pulsed nuclear magnetic resonance (NMR) technique, being ±15% or less, and

the carbon fiber composite material having a dynamic modulus of elasticity (E′) at 150° C. of 30 MPa or more and an elongation at break (EB) of 140% or more,

wherein an amount of the vapor-grown carbon fibers in the carbon fiber composite material is 15 to 60 wt %.

5. The carbon fiber composite material as defined in claim 4 ,

wherein the elastomer has a molecular weight of 5000 to 5,000,000; and

wherein a network component of the elastomer in an uncrosslinked form has a spin-spin relaxation time (T 2 n ), measured at 30° C. by a Hahn-echo method using a pulsed nuclear magnetic resonance (NMR) technique, of 100 to 3000 microseconds.

6. The carbon fiber composite material as defined in claim 4 ,

wherein the dynamic modulus of elasticity (E′) of a sheet of the carbon fiber composite material extruded from a mixer in a first direction includes a first dynamic modulus of elasticity (E′(L)) in the first direction and a second dynamic modulus of elasticity (E′(T)) in a direction which is perpendicular to the first direction and is a width direction of the carbon fiber composite material; and

wherein an orientation ratio (E′(L)/E′(T)) of the first dynamic modulus of elasticity (E′(L)) to the second dynamic modulus of elasticity (E′(T)) is 2 or less.