MULTIFUNCTIONAL PROPERTIES OF COMPOSITES WITH CONDUCTIVE COATINGS USING RENEWABLE PLANT BASED GRAPHENE FROM BIOMASS WASTE SOURCES

Renewable, plant-based graphene nanoparticles (pGNP) can be utilized as a multifunctional reinforcement with comparable properties to mineral graphenes with substantially improved usability and reduced environmental impact. In this study we examined the effects of feedstock selection on pGNP properties and the impacts on multifunctional composite properties, which included surface conductivity, electromagnetic interference (EMI) shielding and fire resistance. Multifunctional pGNP coatings were prepared using a polyurethane material system in which impacts to crosslinking are measured. Coatings were applied to PA6 woven glass fiber composites via spray application. pGNP properties measured include elemental composition, degree of graphitization, surface functional groups, and ash content and composition. Ash composition of biomass feedstocks is shown to have a strong impact of graphitization and pGNP multifunctionality. The pGNP/PU coating showed significant impacts to the molecular structure of the polymer, with an increase to tensile strain along the polymer backbone and a reduction in chain vibrations. Surface conductivity of the composite increased by seven orders of magnitude with the addition of pGNP/PU coating with increased EMI attenuation. Torch testing of coated composites demonstrated increased flame resistance due to charring behavior on the surface which provided for reduced through thickness heating. These results demonstrate the potential of converting biomass waste into valuable nanofiller that can be used for enhancing the functional properties of structural polymer composites.