Carbon nanotube / graphene composites

1. An electrically conductive composite material, comprising:

carbon nanotubes and graphene nanoplatelets within a polymer matrix; wherein the polymer matrix is an epoxy matrix;

wherein a majority of the carbon nanotubes have lengths in the range of 20 μm to 150 μm;

wherein the carbon nanotubes form of the order of 0.02 wt. % of the composite material; and

wherein the graphene nanoplatelets form in the range of 0.02.wt % to 0.06 wt. % of the composite material.

2. The electrically conductive composite material according to claim 1 , wherein the graphene nanoplatelets form of the order of 0.04 wt. % of the composite material.

3. The electrically conductive composite material according to claim 1 , wherein the majority of carbon nanotubes have a length greater than 30 μm.

4. The electrically conductive composite material according to claim 3 , wherein the majority of carbon nanotubes have a length greater than 40 μm.

5. The electrically conductive composite material according to claim 4 , wherein the majority of carbon nanotubes have a length greater than 50 μm.

6. The electrically conductive composite material according to claim 1 , wherein the majority of graphene nanoplatelets have a diameter in the range of 0.25 μm to 1 μm.

7. The electrically conductive composite material according to claim 6 , wherein the graphene nanoplatelets have an average diameter of the order of 0.5 μm.

8. The electrically conductive composite material according to claim 1 , being isotropic.

9. The electrically conductive composite material according to claim 1 , comprised in an article.

10. An electrically-conductive composite material, comprising:

carbon nanotubes and graphene nanoplatelets within a polymer matrix; wherein the polymer matrix is an epoxy matrix;

wherein a majority of the carbon nanotubes have lengths in the range of 20 μm to 150 μm;

wherein the carbon nanotubes form in the range of 0.2 wt. % to 0.3 wt. % of the composite material; and

wherein the graphene nanoplatelets form in the range of 0.005 wt. % to 0.04 wt. % of the composite material.

11. The electrically conductive composite material according to claim 10 , wherein the graphene nanoplatelets form of the order of 0.02 wt. % of the composite material.

12. The electrically conductive composite material according to claim 11 , wherein the carbon nanotubes form of the order of 0.3 wt. % of the composite material.

13. The electrically conductive composite material according to claim 10 , comprised in an article.

14. A composite production method, comprising:

preparing, by a high shear mixing process, a mixture comprising carbon nanotubes and graphene nanoplatelets within a resin; wherein the resin is an epoxy resin;

wherein a majority of the carbon nanotubes have lengths in the range of 20 μm to 150 μm;

wherein the carbon nanotubes form of the order of 0.02 wt. % of the composite material; and

wherein the graphene nanoplatelets form in the range of 0.02 wt. % to 0.06 wt. % of the mixture.

15. The method according to claim 14 , wherein the high shear mixing process is carried out at around 4500 rpm for about 20 minutes.

16. The method according to claim 14 , further comprising:

adding a hardener to the resin;

subjecting the mixture to a further high shear mixing process that is carried out at around 4500 rpm for about 5 minutes; and

subjecting the mixture to a stirring process that is carried out at around 500 rpm for about 5 minutes.

17. The method according to claim 14 , further comprising subjecting the mixture to a degassing process that is carried out at about 60° C. for about 1 hour, under negative pressure.

18. The method according to claim 14 , further comprising transferring the mixture to a mold and curing the resin.