An investigation on industrial adhesive nano-modified by graphene nanoplatelets under extreme environmental conditions

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It is a well-known fact that extreme environmental conditions are the cause of a large number of adhesive failure. To be able to minimize such problem, an experimental study on graphene nanoplatelets (GNP) effects into an industrial mono component adhesive was proposed. The nano-modified adhesive was used into single lap joints of galvanized steel commonly employed in automotive industry. Due to SKP-456LB's large viscosity and the GNP large concentration (up to 3 wt%), an alternative method for nanostructure dispersion was employed. A grease worker, an equipment commonly employed for lubricant consistency and shear stability testing, was employed as a homogenization device. To be able to understand how the GNP nanostructures affected SKP-456LB's overall mechanical response to severe environmental conditions, four sets of single lap joints (SLJ) were prepared and tested after environmental exposure. The environmental conditions can be summarized as, i.e. base line (no exposure to extreme environment), 500 h at 100C, 500 h at 95% relative humidity and temperature of 40C, and 500 h under salt spray. The GNP addition to pure SKP-456LB increased the apparent shear strength by approximately 29%. GNP in small concentrations (1.0 wt%) \ did not provide an improvement on SKP-456LB adhesive mechanical properties. This phenomenon could be due to agglomeration/cluster formation. The remaining load bearing for the 3 wt % concentration (around 75% of the baseline data), after exposition to harsh environment, was still larger than the ones with GNP smaller concentration; The addition of carbon based nanostructures led to a mix failure mode where cohesive and adhesive modes were acting at the same time.