EFFECT OF EPOXY MATRIX VISCOSITY ON THE DISPERSION OF GPL GRAPHENE LAYER SEPARATION FOR COATING APPLICATIONS

Abstract

Coatings application is among the most accessible methods of surface modification. Many materials exhibit the desired bulk properties (e.g. mechanical strength), but their surface needs to be protected from the environment to have an additionally functionalized surface - heat and electrically conducting or isolating, optical or aesthetic considerations. 
When adding nanosized materials to a matrix the main concern is the retention of separation of nanoparticles and the prevention of aggregation. In the following study, dispersion of Graphene nanoplatelets (GPL) in bisphenol-a based epoxy is investigated. GPL is initially sonicated in methanol and introduced into a series of liquid epoxies with varying dry weight concentration and thus, varying viscosity. The working hypothesis that increased viscosity aids to stabilize the suspension and delamination of graphene layers, has been confirmed. The samples have been characterized by Transmission Electron Microscopy (TEM) and Raman spectroscopy. TEM confirms that the best delamination is retained in the most concentrated matrix. Increased Raman signal intensity testifies to the increase of stabile suspended fraction of GPL before coating, which leads to a higher concentration of active additives in the coatings. Furthermore, adhesion and delamination testing by the crosshatch method confirms that adding GPL does not negatively affect the mechanical properties of the coatings, as compared to coatings without the addition of GPL.