Evaluation of mechanical reinforcement in epoxy adhesives using a hybrid triple nanoparticle reinforcement strategy based on MWCNTs, GNPs and nano alumina

The reinforcement of adhesives with nanoparticles has emerged as a promising strategy for enhancing their mechanical performance. Although numerous studies have explored single- and double-nanoparticle reinforcement systems, the simultaneous incorporation of three distinct nanoparticles within a single adhesive matrix—referred to here as triple-particle reinforcement—remains largely unexplored. In this context, the present research aims to take an initial step in evaluating the influence of triple-particle reinforcement with three types of nanoparticles including multi-walled carbon nanotubes (MWCNTs), graphene nanoplatelets (GNPs), and nano-alumina on tensile strength of Axson-Sika Adekit A 140-1 epoxy adhesive. Four groups of specimens were prepared to evaluate tensile strength of the bulk adhesive including neat adhesive, adhesives with single-type reinforcement using either MWCNTs, GNPs, or nano-alumina (at 0.1, 0.3, 0.5, and 0.7 wt%), adhesives with double-type reinforcement combining two nanoparticles in equal proportions, and adhesives with triple-particle reinforcement involving all three nanoparticles at equal mixing ratios across the same weight contents. The results showed that, in the double-type category, the MWCNT-GNP combination at 0.5 wt% led to the best performance, surpassing the best single-type result by 17%. It was found that the triple-particle reinforcement using a dispersion method as in the single- and double-type reinforced specimens resulted in approximately similar tensile strength compared to that of the double-type nanoparticle reinforcement. However, by modifying the dispersion method, the tensile strength was approximately equal to that of the double-particle nanoparticle reinforcement group.