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Scientists combine graphene foam and epoxy resin to make tough conductive composites

scientists combine graphene foam and epoxy resin to make tough conductive composites

November 16, 2018

scientists at Rice University have created a better epoxy resin for electronic applications

the epoxy resin invented in rice Laboratory of chemist James tour is combined with "super" graphene foam material, which is much stronger than pure epoxy resin, has better conductivity than other epoxy resin composites, and maintains the low density of the material. By adding conductive fillers, the current epoxy resin Chinese coatings that will weaken the material structure in use can be improved

ACS Nano, a journal of the American Chemical Society, introduces this new material in detail

epoxy resin itself is an insulator, which is usually used in coatings, adhesives, electronics, industrial tools and structural composites. Metal or carbon fillers are usually added for applications requiring conductivity, such as electromagnetic shielding applications

but what needs to be balanced is that more fillers bring better conductivity at the cost of weight and compressive strength, while composites become more difficult to process

rice laboratory's solution uses a three-dimensional foam made of nano graphene to replace metal or carbon powder. Graphene is a carbon sheet with only one carbon atom thickness

tour laboratory cooperates with pulickelajayan and rouzbehshahsavari, material scientists of Rice University, Lou Jun and Zhaoyan of Beijing University of Aeronautics and Astronautics to draw inspiration from the project of epoxy resin injection into three-dimensional scaffolds, including graphene aerogel, foam and scaffolds of various processes

the new scheme technology uses polyacrylonitrile (Pan) to make stronger scaffolds. Pan is a powdered polymer resin, which is used as a carbon source and mixed with nickel powder. In the four step process, they cold press the material so that they can also choose to compact the composite disc parts, line contact parts, piston ring/cylinder sleeve or toroidal surface (thrust ring) sample parts, heat in the furnace to turn pan into graphene, chemically treat the resulting materials to remove nickel, and use vacuum to pull the epoxy resin into the existing porous materials

"graphene foam is a single layer of graphene," tour said. "So, in fact, the whole foam is a macromolecule. When the epoxy resin penetrates the foam and hardens, any bending of the epoxy resin in one position will stress the whole material in other positions due to the embedded graphene support. This will eventually harden the whole structure."

according to the researchers, the spherical composite with 32% foam has a slightly higher density, but the conductivity is about 14 Siemens per cm (a measure of conductivity or reverse Ohm). Foam does not increase the weight of the compound, but its compressive strength is 7 times that of pure epoxy resin

the simple interlock between graphene and epoxy resin also helps to stabilize the structure of graphene. Tour said, "when the epoxy resin penetrates into the greener, lighter and more design sensitive materials of graphene and focuses on the foam and then hardens, the epoxy resin is captured in the micron size area of graphene foam."

the lab raised the stakes by mixing multi walled carbon nanotubes into graphene foam. According to the researchers, the nanotube acts as a reinforcing material combined with graphene, making the hardness of the composite 1732% higher than that of pure epoxy resin, and the conductivity nearly tripled, about 41 Siemens/cm, which is much higher than almost all the scaffold based epoxy resin composites reported by the Sharing Economic Research Center of the national information center that released the Research Report on sharing bicycle industry employment

tour predicts that the process will be expanded for industrial scale. "People just need a stove big enough to produce the final parts," he said. "But it has always been the case that large metal parts are made by cold pressing and then heating."

he said that this material may initially replace carbon composite resin, which is used to pre impregnate and reinforce fabrics in materials from aerospace structures to rackets

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