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What are composite materials?

Composite materials (also referred to as composition materials, or simply composites) are materials formed by combining two or more materials with different properties to produce an end material with unique characteristics. These materials do not blend or dissolve together but remain distinct within the final composite structure. Composite materials can be made to be stronger, lighter or more durable than traditional materials due to properties they gain from combining their different components.

Most composites are made up of two materials - the matrix (or binder) surrounds a cluster of fibers or fragments of a stronger material (reinforcement). A common example of this structure is fiberglass, which was developed in the 1940’s to be the first modern composite and is still in widespread use. In fiberglass, fine fibers of glass, which are woven into a cloth of sorts, act as the reinforcement in a plastic or resin matrix.

composite crossection image

While composite materials are not a new concept (for example, mud bricks, made from dried mud embedded with straw pieces, have been around for thousands of years), recent technologies have brought many new and exciting composites to existence. By careful selection of matrix and reinforcement (as well as the best manufacturing process to bring them together) it is possible to create significantly superior materials, with tailored properties for specific needs. Typical composite materials include composite building materials like cement and concrete, different metal composites, plastic composites and ceramic composites.

How are composite materials made?

The three main factors that help mold the end composite material are the matrix, reinforcement and manufacturing process. As matrix, many composites use resins, which are thermosetting or thermosoftening plastics (hence the name ‘reinforced plastics’ often given to them). These are polymers that hold the reinforcement together and help determine the physical properties of the end composite.

layers inside a composite image

Thermosetting plastics begin as liquid but then harden with heat. They do not return to liquid state and so they are durable, even in extreme exposure to chemicals and wear. Thermosoftening plastics are hard at low temperatures and but soften with heat. They are less commonly used but possess interesting advantages like long shelf life of raw material and capacity for recycling. There are other matrix materials such as ceramics, carbon and metals that are used for specific purposes.

Reinforcement materials grow more varied with time and technology, but the most commonly used ones are still glass fibers. Advanced composites tend to favor carbon fibers as reinforcement, which are much stronger than glass fibers, but are also more expensive. Carbon fiber composites are strong and light, and are used in aircraft structures and sports gear (golf clubs and various rackets). They are also increasingly used to replace metals that replace human bones. Some polymers make good reinforcement materials, and help make composites that are strong and light.

The manufacturing process usually involves a mould, in which the reinforcement is first placed and then the semi-liquid matrix is sprayed or poured in to form the object. Moulding processes are traditionally done by hand, though machine processing is becoming more common. One of the new methods is called ‘pultrusion’ and is ideal for making products that are straight and have a constant cross section, like different kinds of beams. Products that of thin or complex shape (like curved panels) are built up by applying sheets of woven fiber reinforcement, saturated with matrix material, over a mould. Advanced composites (like those which are used in aircraft) are usually made from a honeycomb of plastic held between two sheets of carbon-fiber reinforced composite material, which results in high strength, low weight and bending stiffness.

Where can composites be found?

Composite materials have many obvious advantages, as they can be made to be lightweight, strong, corrosion and heat resistant, flexible, transparent and more according to specific needs. Composites are already used in many industries, like boats, aerospace, sports equipment (golf shafts, tennis rackets, surfboards, hockey sticks and more), Automotive components, wind turbine blades, body armour, building materials, bridges, medical utilities and others. Composite materials’ merits and potential assures ample research in the field which is hoped to bring future developments and implementations in additional markets.

applications of composites image

Modern aviation is a specific example of an industry with complex needs and requirements, which benefits greatly from composite materials’ advantages. This industry raises demands of light and strong materials, that are also durable to heat and corrosion. It is no surprise, then, that many aircraft have wing and tail sections, as well as propellers and rotor blades made of composites, along with much of the internal structure.

What is graphene?

Graphene is a two-dimensional matrix of carbon atoms, arranged in a honeycomb lattice. A single square-meter sheet of graphene would weigh just 0.0077 grams but could support up to four kilograms. That means it is thin and lightweight but also incredibly strong. It also has a large surface area, great heat and electricity conductivity and a variety of additional incredible traits. This is probably why scientists and researchers call it “a miracle material” and predict it will revolutionize just about every industry known to man.

Graphene and composite materials

As was stated before, graphene has a myriad of unprecedented attributes, any number of which could potentially be used to make extraordinary composites. The presence of graphene can enhance the conductivity and strength of bulk materials and help create composites with superior qualities. Graphene can also be added to metals, polymers and ceramics to create composites that are conductive and resistant to heat and pressure.

graphene and tin layered composite image

Graphene composites have many potential applications, with much research going on to create unique and innovative materials. The applications seem endless, as one graphene-polymer proves to be light, flexible and an excellent electrical conductor, while another dioxide-graphene composite was found to be of interesting photocatalytic efficiencies, with many other possible coupling of materials to someday make all kinds of composites. The potential of graphene composites includes medical implants, engineering materials for aerospace and renewables and much more.

Further reading

Latest Graphene Composite news

Manchester U team shows the influence of pre- and post-dispersion on the properties of GNP-enhanced epoxy

Mar 23, 2017

Researchers from The University of Manchester have conducted a study that presents a review of the three steps of manufacturing graphene/epoxy nano-composites. The possible pre-treatments of nanoparticles before dispersion are introduced, and their influence on the final nanocomposite properties discussed.

SEM images of fracture surface of aligned GNP based epoxy compositeSEM images of fracture surface of aligned GNP based epoxy composite

The study stresses interesting results, among which are improvements in various characteristics via the use of GNPs. For instance, an improvement of the thermal diffusivity of 220% was seen when compared to a non-oriented GNP epoxy sample. The work demonstrates how the addition of functionalized graphene platelets to an epoxy resin will allow it to act as electrical and thermal conductor rather than as insulator. The mechanical properties of functionalized GNP/epoxy composites show improvement of the interfacial bond.

Directa Plus announces graphene-enhanced eyewear collection by Ray-Ban collection with G+ inside

Mar 14, 2017

Directa Plus, a producer and supplier of graphene-based products for use in consumer and industrial markets, recently announced that its graphene-based materials have been selected by Luxottica Group, a company that designs, manufactures and sells eyewear, to enhance a new range of Ray-Ban glasses.

Directa Plus and Ray-Ban produce graphene-enhanced eyewear image

Ray-Ban updates that during the creation process of this collection, every detail—from design to production techniques—has been studied to make the best use of the characteristics of graphene. The molds, for example, were designed with special care to facilitate equal distribution of the material, a special mixture of resins and graphene, all over the front of the frame.

Graphene Supercapacitors Market Report

Graphene-Enhanced Composite Materials Improve Lightning-Strike Performance

Mar 14, 2017

Haydale logoThe following is a sponsored post by Haydale

Haydale Composite Solutions are pleased to announce the production of graphene-enhanced electrically-conductive carbon fibre-reinforced composite materials with improved resistance to damage from a severe lightning-strike event.

Carbon fibre-reinforced composite materials, as used in many aerospace structures and components, are vulnerable to damage from lightning strikes. However, the addition of functionalised nano materials to the epoxy resin through the use of Haydale’s patented plasma functionalisation process, HDPlas™, has been demonstrated to significantly improve the electrical conductivity of the epoxy resin which allows the laminate to dissipate the energy of the lightning strike throughout the structure thereby reducing the localised heating which causes damage in a lightning-strike event. Importantly, these improvements have been achieved without any major issues with existing manufacturing processes.

Applied Graphehe Materials updates on progress of its graphene work

Mar 05, 2017

Applied Graphene Materials logoApplied Graphene Materials, in a recent update, said it made "significant progress" in all of its core markets of composites, coatings, oils and lubricants. Among the reported highlights of its work is its graphene-enhanced epoxy prepreg system MTC9800 to be shown at the JEC World exhibition later this month, after a year and half collaboration with SHD Composites.

In addition, the company has recently completed the first phase of a development project investigating the application of its graphene for resin infused Aerospace structures. During 2016 it continued work on its development program with Airbus Defence and Space, a division of Airbus Group SE, although details of this work are still subject to a non-disclosure agreement.

Graphene 3D Lab adds graphene-silver epoxy to its G6-Epoxy product line

Feb 28, 2017

Graphene 3D Labs logoGraphene 3D Lab, a leader in the development, manufacturing and marketing of proprietary composites and coatings based on graphene and other advanced materials, has announced an addition to its G6-Epoxy line of adhesives. This new product, G6E-GSTMepoxy, is a highly electrically conductive adhesive based on the combination of graphene and silver additives. It reportedly has a volume resistivity as low as 0.0001 Ω·cm and can be cured at room temperature or more rapidly at elevated temperatures. G6E-GSTM bonds well to a wide variety of substrates including metals, composites, ceramics, and glass.

The graphene filler is said to enhance the electrical conductivity of the epoxy and prevent the propagation of cracks, improving the material’s durability and fatigue resistance. This is especially important when bonding dissimilar materials subjected to rapid temperature variations. This feature improves impact resistance of the bond and also helps mitigate potential damage caused by vibration.