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Today's graphene market. Graphene was first separated as a separate carbon layer in 2004, and now there are approximately 200 suppliers worldwide who commercially supply it in the form of additive powders, aqueous solutions, and flakes.

In 2004, researchers from the University of Manchester, UK, separated and identified graphene for the first time. They used tape to separate the graphite into a separate carbon layer. In 2010, Andre Geim and Kostya Novoselov, the founders of graphene, were awarded the Nobel Prize in Physics. Ten years later, the application of graphene reinforced composite materials (from aramid nanofiber reinforced supercapacitors for electric vehicle batteries to aerospace composite material tools and low-temperature pressure vessels) continues to make headlines. This material itself has been commercialized for about 10 years, but according to Terrance Barkan, Executive Director of the Graphene Committee (New Bern, North Carolina, USA), the commercialization path of graphene has significantly accelerated in the past few years. In fact, the Graphene Committee reported that over 2300 graphene related patents have been approved in just the past 12 months.

Graphene is known as a "magical material", known for its impressive mechanical quality, high cost, and immature supply chain. Therefore, the Graphene Committee and other institutions in the graphene industry are helping professionals in the composite materials industry to re-examine what graphene is and its potential in composite material applications.

Form and attributes

Graphene is a two-dimensional, planar carbon atomic sheet located in a dense honeycomb lattice. Although the purest graphene is only one atom thick, graphene can also be made into thin sheets containing up to 10 or more carbon layers. Graphene producers produce graphene in several different ways. One method is to peel off a separate carbon layer from raw materials such as mineral graphite. Alternatively, the carbon layer can be deposited onto the substrate from gas raw materials such as methane (referred to as chemical vapor deposition). CVD produces the thinnest single-layer graphene; Most large or multi-layer graphene products used in composite material applications are exfoliated from graphite.

Terence Bacan stated that after Geim and Novoselov won the Nobel Prize in 2010, companies and laboratories demanded the development of applications using graphene, as it has been proven to be the strongest, hardest, and thinnest material to date.

In composite materials, graphene is commonly used as an additive in resin matrices and other materials to enhance various mechanical properties, including conductivity and thermal conductivity, durability, flexibility, stiffness, UV resistance, weight reduction, and fire resistance. Terence Bacan pointed out that the use of graphene in composite material applications is particularly important as it can reduce interlayer shear failure, eliminate microcracks in composite laminates, and improve impact resistance/toughness. "This is basically magic," he concluded.

Unlike other additives, graphene only needs to be added in a very small amount to achieve the desired performance.

Terence Bacan pointed out that using graphene also has an inherent sustainability factor. Graphene itself can be recovered from waste such as biodiesel, and its durability can extend the lifespan of materials or products, making them more sustainable. In addition, graphene is pure carbon, avoiding the potential toxicity of some other chemicals or additives used in the resin matrix.

The form of graphene

The final form of graphene products first depends on the number of carbon layers that make up the material. Barkan stated that although "primitive" graphene has only one atomic layer thickness, materials with carbon atomic layers not exceeding 10 are still referred to as graphene on the market. Graphene is typically divided into extremely thin layers of graphene (vFLG, 1-3 layers of carbon), thin layers of graphene, multilayer graphene (MLG, 2-10 layers), or graphene nanosheets (GNP, which can be stacked from multiple layers of graphene sheets). In addition to the carbon layer, graphene has several commercial forms, including graphene oxide (GO, a compound of carbon, oxygen, and hydrogen); Reduced graphene oxide (rGO, which has less oxygen and more carbon); Graphene powder, solution or paste; Graphene nanosheets (thickness between 1-3 nanometers, lateral dimensions within the range of 100 nanometers to 100 micrometers); And functional fossil graphene, which adds elements to the surface or edges of graphene for certain applications. An example of functional fossil graphene is plasma treated graphene produced by Haydale (Ammanford, UK). According to Gemma Smith, Haydale's global marketing director, it is said to help prevent agglomeration when dispersed into resin.

Graphene and carbon nanotubes. Carbon nanotubes (CNT carbon nanotubes) and graphene are sometimes concentrated together because both are nanomaterials composed of carbon and are commonly used as additives in composite materials. They can share similar attributes, but in different forms. CNT is a three-dimensional carbon tube that can have various thicknesses and lengths, while graphene is a two-dimensional carbon sheet. Some suppliers produce both graphene and carbon nanotubes simultaneously.

Generally speaking, the fewer layers, the higher the price. According to the Graphene Committee's data, graphene with 1-2 layers costs up to $100000 per square meter (although the commercial price is much lower), while multi-layer graphene costs between $50-1500 per kilogram. Terence Bacan said that for many composite material applications, multi-layer graphene or graphene nanosheets exhibit sufficient performance. Terence Bacan also pointed out that graphene molecules are very small and completely encapsulated in resin - they cannot "detach" or "liberate" during the manufacturing process.

Any form of graphene can be dispersed for application in various ways using functionalized, composite, or various solvents and surfactants. Barkan pointed out that one obstacle to the commercialization of graphene is that for many applications, dispersion methods remain a challenge to understand and execute.

According to Terence Bacan, for composite material applications, multi-layer nanosheets (1-5 nanometers thick) in the form of black powder are typically mixed into liquid resins or hardeners. Barkan said that unlike many other types of additives, graphene only needs to be added in very small amounts to achieve the desired performance - typically less than 1% by weight, typically less than 0.1% by weight or lower. Barkan pointed out that some companies are also adding graphene to fiber sizing for certain applications, and can even weave it into fibers - some nylon fiber suppliers have already done so.

Terrence Bacan said, "Graphene can be used in almost any plastic, resin, or solvent you can think of.". This includes thermoplastic materials, where graphene typically combines into thermoplastic beads or particles during the melt mixing stage. Terence Bacan said that the combination of graphene and thermoplastic plastics increases the operating temperature of the resin and prolongs its lifespan.

Suppliers and Applications

According to Terrence Bacan, there are currently over 200 companies claiming to supply graphene. However, he said that about 80% of them are small-scale laboratory scale operations. He estimates that there are currently around 30 industrial scale graphene producers operating, and new companies frequently enter the market.