Graphene is the material of the future. It has been the material of the future and – at the rate things are going – it might always be the material of the future. Some 3D printing material manufacturers, however, are really trying to make it the materials of the present by offering a range of thermal extrusion filaments (and maybe soon even some laser sintering powders) for 3D printing graphene, which use graphene as a reinforcement in a thermopolymer matrix. Lets see which they are and what they can offer today (and what they will offer tomorrow).
The premise is that graphene – an atomic-scale honeycomb lattice made of carbon atoms – is really challenging to 3D print by thermal extrusion.
If you add too much the filament becomes too viscous however if you put too little you don’t fully benefit from its properties. Which are they? Mainly lightweight and strength excellent strength to weight ratio) and electrical conductivity. Graphene is undoubtedly emerging as one of the most promising nanomaterial because of this unique combination of properties, which makes it ideal for applications ranging from electronics to optics, sensors, and biodevices.
Graphene-based nanomaterials have many promising applications in energy-related areas. Just some recent examples: Graphene improves both energy capacity and charge rate in rechargeable batteries; activated graphene makes superior supercapacitors for energy storage; graphene electrodes may lead to a promising approach for making solar cells that are inexpensive, lightweight and flexible; and multifunctional graphene mats are promising substrates for catalytic systems.
3D Printing Graphene Today
Today, in 3D printing, there are ongoing research projects to develop 3D printable graphene-based composites in both thermoplastic filaments and powders as well as in photopolymer resins. Even though graphene is expected to offer advanced properties in all these processes (especially powder bed fusion) there are today only a few commercial applications for graphene composites in 3D printing.
Graphene 3D Labs
The first was Calverton, New York-based Graphene 3D Lab. Its Black Magic 3D Conductive Graphene is a PLA/Graphene composite specifically designed to 3D print electrically conductive components using almost any commercially available FFF desktop 3D printer. Graphene 3D Lab itself is a leader in the development and manufacturing of composite materials based on graphene. The 3D Printing Division of Graphene 3D Lab focuses on the rapid commercialization of 3D printing technologies via nano-length fiber composites for open FFF 3D printing systems. Their goal is to develop technologies for 3D printing circuitry and functional components, as well as enabling the 3D printing of entire operational devices in a one-step, fully computerized process.
Graphene 3D’s conductive 3D printing filaments are produced from natural graphite, and according to the company set the record for the lowest electrical resistivity. The Conductive Graphene filament is offered in black, has volume resistivity of 1 ohm-cm, and is sold in 100g spools for roughly $55. Potential applications include capacitive (touch) sensors for proximity, position, humidity, fluid levels, and acceleration. Another application of conductive graphene filament is in the creation of electrically conductive circuitry for use in electronics such as interfacing computers, Arduino boards, LED’s and wearable electronics.
The second is materials experts PMG 3D Technologies (an acronym that stands for Plastic Metal Graphene), based in Shanghai in China. It is a global materials, technologies and services provider for the 3D printing industry, providing perhaps the largest range of graphene based filaments on the market today, along with polymers, metals and ceramics. The company can provide systematic and innovative optimization solutions for materials, structure and density as well as use these materials to manufacture parts for aviation, medical products and art models.
The graphene based filaments include different grades (meaning different concentrations, from 1 ppm to 5000 ppm) of GraphenePLA and GraphenePVDF. GraphenePLA is nano-reinforced, high-intensity and multi-functional composite, while GraphenePVDF is nano-reinforced, high temperature resistant, corrosion-resistant composite which is commonly used in green energy industry.
PMG stands out as one of the first companies to successfully develop graphene series 3D printing materials based on GPLA (with registered GraphenePLA trademark) it is also the the first company to successfully developed 3D printing series materials GPVDF and apply PVDF 3D printing material to the green energy industry (solar energy, power station, and green architecture industries).
PMG’s founder, Dr. Zhang, said that they have been able to 3D print using composite filaments with very high concentrations of graphene and that they are developing a graphene-specific extrusion 3D printer.
The GraphenePLA and GrapheneGPVF filaments are currently available with different concentrations. The base version has of less than 1 part per million, which is arguably a bit of a marketing stunt even though the company says it does offer some benefits in terms of strength toughness and stiffness. On the other hand, the 5,000 part per million (GPLA 5K and GPVF 5K ppm) filaments show significantly improved mechanical properties and strength. PMG also offers another filament with 5,000 ppm concentration – the GPLA-C – which has been engineered for excellent electrical conductivity.
FiloAlfa and DirectPlus
One more project involving graphene comes from Italian filament manufacturer FiloAlfa, which collaborated with Italian graphene leaders DirectPlus to develop the Grafilon 3D filament. This commercially available material, currently using graphene mostly for its aesthetic properties and to increase PLA properties (elastic modulus +34%, tensile strength +23% and elongation at break +28%), is meant as the starting step toward the development of a new family of filaments with higher concentrations of graphene.
Established in 2005, Directa Plus has a unique and patented technology process and a scalable and portable manufacturing model. They produce graphene-based products at the factory near Milan, Italy, and can set up additional production at customer locations to reduce transport costs, waste and time-to-utilisation.
3D Printing Graphene Tomorrow
As for other, more futuristic 3D printing implementations of composite graphene materials, tow very interesting areas of exploration are laser sintering powders and photopolymer resins for stereolithography.
3D Printing Graphene by Stereolithography
A study conducted last year by scientists from Kansas State University, SUNY Buffalo and Purdue University researchers demonstrated the first three-dimensional printed graphene oxide (GO) complex structures by stereolithography (SLA). The resulting composite material presented a good combination of increased strength and ductility.
Adding only 0.2% of graphene oxide to EnvisionTEC’s Pic100 castable resin material, the tensile strength of the composite was increased by 62.2% and elongation increased by 12.8%.
To achieve the ideal dispersion of the GO particles into the polymer matrix, the scientists used the solution intercalation method, where the graphene is dispersed in solvent before addition of the polymer resin. The 3D printing process was carried out by bottom-up mask projection based stereolithography (MPSL), which is more commonly known as DLP stereolithography in the commercial sphere.
Investigating the strengthening mechanism of the 3D printed structure in terms of tensile strength and elastic modulus (stress vs strain), the researchers found that an increase in ductility of the 3D printed graphene composites is related to increase in crystallinity of GO reinforced polymer. Nevertheless, commercial applications of the graphene composite are yet unclear, due to the costs of both the graphene and streolithography systems.
3D Printing Graphene by Laser Sintering (SLS)
Now that new open materials laser sintering systems have been arriving on the market from companies like Ricoh and Prodways, third party AM powder material manufacturers are hard at work developing new, high perfromance composite powders. Currently the focus is primarily on composites of nylon (PA12) and carbon or galss fiber. However one pioneering company in this field, Italy based CRP Group is currently in very early stages of developing a graphene based powder for SLS. The company has recently acquired a Ricoh AM5500 system, to complement the range of SLS systems it currently operates. We don’t know when – and if – it will ever reach the market but we do know that it shows great promise, after all graphene is and will always be the material of the future.