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.

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

First Graphite joins Australian graphene research hub

Jul 23, 2017

First Graphite logo imageFirst Graphite, the Australia-based graphite miner and graphene producer, recently announced that it has become a Tier 1 partner to the Australian Research Council Research Hub for Graphene Enabled Industry Transformation (ARC Graphene Research Hub).

The ARC Graphene Research HUB aims to provide knowledge, innovative research and commercial development of graphene technologies across broad areas. Under the Terms of the ARC Hub agreement FGR will focus on the areas of fire retardants, where the Company already has global licence to exploit the technology, development of conductive graphene coatings and development of graphene polymer composites.

Graphenea announces new graphene oxide pilot plant

Jul 22, 2017

Graphenea recently announced the opening of a new graphene oxide (GO) pilot plant with 1 tonne per annum production capacity. The new plant is meant to significantly increase production capacity for Graphenea (which is already producing GO dispersions, powders, and films), while also allowing for higher quality and batch-to-batch reproducibility. The plant reportedly houses in-line quality control of each individual batch.

Graphenea's new pilot plant for GO image

Graphenea stated that although the production volume is large, the new plant can accommodate custom requirements regarding flake size, oxygen levels, and other specifications. Orders for multi-kilogram quantities will be processed with short delivery times. The production capacity is multiplied by 20 times compared to capabilities before the pilot plant, allowing for development and industrial scale supplies.

Graphene Handbook

NanoXplore plans a 10,000 ton graphene powder facility

Jul 19, 2017

Group NanoXplore has recently announced plans to become a public company, with a business strategy of acquiring companies in order to introduce graphene to the products. NanoXplore says it is on track to offer graphene at $10/kg. We recently discussed this goal with the company’s CEO, Dr. Soroush Nazarpour.

NanoXplore Hexo-G graphene powder photo

Dr. Soroush explains that at the simplest level, commercialization of graphene requires either developing new applications and products, or replacing existing products. There are many examples of graphene companies pursuing each of these approaches. NanoXplore is one company targeting existing products. They plan to dramatically reduce the price of graphene so that it can compete with carbon black.

Researchers in India develop a graphene-silver-pyyrole composite for supercapacitors

Jul 16, 2017

Researchers at the India Institute of Technology, Kharagpur, have developed a new graphene, silver and pyyrole nanocomposite material suitable for making supercapacitors.

The nanomaterial was made of a graphene sheet onto which silver nanoparticles, each about 15-20 nanometers wide, had been embedded uniformly. The material was shown to have a high specific capacitance of 472 farad per gram at a current density of 0.5 amperes per gram. It could retain 95% of its capacitance after 1,000 consecutive charge-discharge cycles.

Graphene/cellulose nanofiber hybrid sensor to efficiently detect alcohol

Jul 14, 2017

An international group of researchers from Saudi Arabia, China and the US have developed a graphene-bacterial cellulose nanofiber (GC/BCN) hybrid sensor to detect alcohol (ethanol) with great efficiency. The sensor was described as flexible, transparent, highly sensitive and with an excellent alcohol recognition performance. Electrical tests in different liquid environments were performed, with remarkable results.

The researchers created a composite thin film composed of graphene and bacterial cellulose nanofibers. In this material, the bacterial cellulose nanofibres act as the host and the graphene as the filler material. Due to its excellent conductive properties, it was reported that graphene does not require the addition of a conductive filler material, unlike many composites. The Researchers constructed the composite using a combination of wet chemical, blending, sonication (Cole-Parmer), centrifugal (Centrifuge 5810, Eppendorf), dialysis and sputtering (Equipment Support Co) methods.

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