Structural nanoskin based on carbon nanosphere chains

Abstract

A multifunctional structural nanoskin is being developed using Carbon Nanosphere Chains (CNSC) and a polymer. Three suites of properties are particularly important in developing the nanoskin; good elastic properties, good electrical properties, and good transducer properties. The CNSC material is first studied in the bulk form. Preliminary results show CNSC are well crystallized graphitic structures with spherical shape connected in chains. The CNSC are almost catalyst free, and are lightweight and hydrophobic. The CNSC morphology is between that of spheres and cylinders. Initial testing was done to characterize the CNSC and to determine if the nanosphere chains can be purified and then dispersed to reinforce an epoxy polymer. The testing involved evaluation of the mechanical properties and electrical conductivity of an epoxy nanocomposite material. A simple analysis of series and parallel fiber reinforcement of polymers was performed first and predicted that limited improvement in stiffness is possible using discontinuous fibers, while a large improvement is possible using continuous fibers. Epoxy nanocomposites were then formed by simultaneously mixing CNSC and epoxy using a shear mixer and ultrasonicator. The elastic properties of the cured nanocomposite showed small improvement with small percentages of the CNSC added to the polymer. On the other hand, compressed CNSC powder has high electrical conductivity. Therefore, a nanoskin material was designed by dispersing CNSC in a solvent, solution casting the solvent into a thin film in a mold, covering the film with epoxy, and closing the mold and curing under pressure. Evaluation of the material is still underway, but the nanoskin has electrical conductivity on one side and is electrically insulating on the other side. A major advantage of the CNSC material is that is can be produced in large quantities at reasonable cost for many potential applications.