Investigation of Plasma-Assisted Functionalization of Graphitic Materials for Epoxy Composites

Abstract

In this study we evaluated the effect of microwave vacuum plasma for the surface functionalization of graphitic fillers (graphite and graphene); we also showed the effect of the functionalization on the mechanical and electrical properties of epoxy composites. Optimized conditions of plasma treatment were defined to obtain high plasma density and increased surface hydrophilicity of the fillers, with high stability of functionalization over time and temperature. However, the extent of such treatments proved to be limited by the high temperatures involved in the curing process of the resin. The use of specific gas mixtures (He/O2) during functionalization and the use of a high surface filler (graphene) can partially limit these negative effects thanks to the higher thermal stability of the induced functionalization. As a consequence, mechanical tests on graphene filled epoxies showed limited improvements in flexural properties while electrical resistivity is slightly increased with a shift of the percolation threshold towards higher filler concentration.

Investigation and Optimization of Vacuum Plasma Treatment of PA66 Fabric for Reduced Fire Retardant Consumption

“…Chamber pressure and fabric-to-plasma nozzle distance were selected according to the findings of a previous study on carbon-based fillers, 38 while the treatment time was varied from 2 to 10 min following the conditions reported in other experiments of vacuum plasma functionalization involving PA fabric. 39 Plasma power generation was varied in the low to high limit range with a 40 W step, since it directly influences the plasma density, momentum, and energy which in turn affect the final efficiency of the functionalization process.…”

“…41 However, He does not provide surface functionalization while pure O 2 produces polar species, but only with temporary stability. On the other hand, their mixture is capable of increasing the surface energy of the treated substrate and improve the stability of the treatment, 38 which are essential prerequisites to promote a higher adhesion of FR during finishing processes.…”

Graphene nanoplatelets/epoxy nanocomposites: A review on functionalization, characterization techniques, properties, and applications

“…111 This method is connected to implementing the hydrophobic character of carbon structures to expand their dispersion with polymer polar matrices. 112 The main advantage of plasma treatment is that this process is not damaging the material, has no impurities, and enhances surface properties without changing the bulk composition. 113 Plasma technology benefits reduced reaction processing times and offer a wide-ranging variety of functional groups, relying on the process parameters compared with chemical modification processes.…”

Innovative surface bio-functionalization by fungal hydrophobins and their engineered variants

“…Different strategies have been studied and optimized according to the nature of the surface to derivatize and the target application. There are plenty of examples in the literature, ranging from physical techniques (i.e., laser ablation, abrasive blasting, evaporation, and ion-assisted deposition) ( Peng et al, 2016 ; Yang et al, 2017 ; Letzel et al, 2019 ; Wolf et al, 2021 ) to chemical treatments (i.e., chemical vapor deposition, plasma-assisted surface oxidation, nitration, hydrolyzation, and amination) ( Javanbakht et al, 2015 ; Boaretti et al, 2020 ), that are commonly used. The mentioned strategies are affected by high costs and environmental impacts due to the inclusion of several time-consuming steps and often using hazardous reagents/solvents under harsh environmental conditions ( Lavilla et al, 2014 ).…”