Exfoliated Graphite Nano-Platelets
Encyclopedia
Exfoliated graphite nano-platelets (xGnP) are new types of nanoparticles made from graphite
. These nanoparticles consist of small stacks of graphene that are 1 to 15 nanometers thick, with diameters ranging from sub-micrometre to 100 micrometres. Since xGnP is composed of the same material as carbon nanotubes, it shares many of their electrochemical characteristics, although not their tensile strength. The platelet shape, however, offers xGnP edges that are easier to modify chemically for enhanced dispersion in polymers.
Composite materials made with polymers, like plastics, nylon
, or rubber
, can be made electrically or thermally conductive with the addition of small amounts of xGnP. These nanoparticles can change the fundamental properties of plastics, enabling them to perform more like metals with metallic properties. These new nanoparticles also improve barrier properties, modulus, and surface toughness when used in composites.
Graphene
is extremely electrically conductive material. In turn, xGnP has a percolation threshold for conductivity of 1.9 wt% in thermoplastic matrix. At densities of 2–5 wt%, conductivity reaches sufficient levels to provide electromagnetic shielding. xGnP can also be combined with glass fibers or other matrix materials to provide sufficient conductivity for electrostatic painting or other applications requiring electrical conductivity.
xGnP significantly outperforms most other forms of carbon in terms of thermal conductivity when used at densities of 20 wt% in control resins. At these densities, xGnP also confers significant electrical conductivity as well as improved mechanical properties to most thermoplastic, thermoset, or elastomeric systems. At lesser densities, xGnP adds thermal stability to a variety of matrix materials.
As opposed to materials like carbon black
, xGnP improves mechanical properties of most composites, particularly stiffness and tensile strength. Elastomeric compounds have been shown to experience increased life and reduced surface wear when reinforced with xGnP.
Because of the platelet shape, xGnP significantly improves the impermeability of composites when used at densities of ~3 wt% or greater. xGnP particles can be aligned using electric field, although alignment is not necessary for use in most extrusion systems. Because xGnP also imparts electrical conductivity at these densities, the resulting composites offer attractive cost savings for applications like fuel lines or fuel tank linings.
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...
. These nanoparticles consist of small stacks of graphene that are 1 to 15 nanometers thick, with diameters ranging from sub-micrometre to 100 micrometres. Since xGnP is composed of the same material as carbon nanotubes, it shares many of their electrochemical characteristics, although not their tensile strength. The platelet shape, however, offers xGnP edges that are easier to modify chemically for enhanced dispersion in polymers.
Composite materials made with polymers, like plastics, nylon
Nylon
Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...
, or rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...
, can be made electrically or thermally conductive with the addition of small amounts of xGnP. These nanoparticles can change the fundamental properties of plastics, enabling them to perform more like metals with metallic properties. These new nanoparticles also improve barrier properties, modulus, and surface toughness when used in composites.
Properties
- Bulk Density: ~0.03-0.15g/cm3
- Electrical Resistivity: ~5×10-5 Ω·cm
- Thermal Conductivity: 3000 W/(m·K)
- Tensile Modulus: ~1000 GPa
- Tensile Strength: ~10-20 GPa
Graphene
Graphene
Graphene is an allotrope of carbon, whose structure is one-atom-thick planar sheets of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal lattice. The term graphene was coined as a combination of graphite and the suffix -ene by Hanns-Peter Boehm, who described single-layer...
is extremely electrically conductive material. In turn, xGnP has a percolation threshold for conductivity of 1.9 wt% in thermoplastic matrix. At densities of 2–5 wt%, conductivity reaches sufficient levels to provide electromagnetic shielding. xGnP can also be combined with glass fibers or other matrix materials to provide sufficient conductivity for electrostatic painting or other applications requiring electrical conductivity.
xGnP significantly outperforms most other forms of carbon in terms of thermal conductivity when used at densities of 20 wt% in control resins. At these densities, xGnP also confers significant electrical conductivity as well as improved mechanical properties to most thermoplastic, thermoset, or elastomeric systems. At lesser densities, xGnP adds thermal stability to a variety of matrix materials.
As opposed to materials like carbon black
Carbon black
Carbon black is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, ethylene cracking tar, and a small amount from vegetable oil. Carbon black is a form of amorphous carbon that has a high surface-area-to-volume ratio, although its...
, xGnP improves mechanical properties of most composites, particularly stiffness and tensile strength. Elastomeric compounds have been shown to experience increased life and reduced surface wear when reinforced with xGnP.
Because of the platelet shape, xGnP significantly improves the impermeability of composites when used at densities of ~3 wt% or greater. xGnP particles can be aligned using electric field, although alignment is not necessary for use in most extrusion systems. Because xGnP also imparts electrical conductivity at these densities, the resulting composites offer attractive cost savings for applications like fuel lines or fuel tank linings.