Scientists combine graphene foam and epoxy resin to make a tough conductive composite material

Scientists at Rice University have created a better epoxy resin for electronic applications.
's epoxy resin, invented at the Rice lab of chemist James Tour, combines with "super" graphene foam materials to be much stronger than pure epoxy resins and conducts electricity better than other epoxy composites while maintaining the low density of the material. By adding conductive fillers, the epoxy resins currently in use that weaken the structure of the material can be improved
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the new material in detail in the journal ACS Nano, a journal of the American Chemical Society.
epoxy resin itself is an insulator and is commonly used in coatings, adhesives, electronics, industrial tools and structural composites. Metal or carbon fillers are usually added for applications that require conductivity, such as electromagnetic shielding applications.
but the trade-off is that more fillers provide better conductivity at the expense of weight and pressure resistance, while composites become more difficult to process.
's solution replaces metal or toner with a three-dimensional foam made of nano-scale graphene, a thin sheet of carbon with only one carbon atom thickness.
Tour Labs, in collaboration with materials scientists Pulickel Ajayan, Rouzbeh Shahsavari of The University of Aeronautics and Astronautics in Beijing, and Zhao Yan, drew inspiration from projects in which epoxy resins were injected into 3D brackets, including graphene aerogels, foams and various process brackets.
new scheme technology is made of a stronger bracket using polypropylene acrylic (PAN), a powdered polymer resin used as a carbon source and mixed with nickel powder. During the four-step process, they press the material cold to make it dense, heat it in the furnace to turn pan into graphene, chemically process the resulting material to remove nickel, and use a vacuum to pull epoxy resin into the existing porous material.
"Graphene foam is a single layer of graphene," Tour said. "So, in fact, the whole bubble is a big molecule. When epoxy penetrates the foam and then hardens, any bend in one position stresses the whole material at other locations due to the embedded graphene bracket. This will eventually harden the entire structure.
According to the researchers, the spherical composite material, which has a foam content of 32%, is slightly denser, but has a conductivity of about 14 Siemens per centimeter (a measure of conductivity or reverse ohms). Foam does not increase the weight of the compound, but makes it seven times stronger than pure epoxy resins.
between graphene and epoxy also helps stabilize the structure of graphene. "When epoxy penetrates the graphene foam and then hardens, the epoxy resin is captured in a micron-sized area of the graphene foam," Tour said.
lab raises the stakes by mixing multi-walled carbon nanotubes into graphene foams. The nanotubes act as reinforcing materials for binding to graphene, making the composites 1732 percent harder than pure epoxy resins and nearly three times more conductive, or about 41 Siemens/cm, far higher than almost all bracket-based epoxy composites reported so far, the researchers said.
Tour expects the process to expand to industrial scale. "People just need a stove big enough to make the final parts, " he says. "But that's always been the case, by cold pressing and then heating to make large metal parts."
said the material could initially replace carbon composite resins, which are used to pre-impregnate and reinforce fabrics in materials from aerospace structures to tennis rackets.