Multi-nationality epoxy adhesives on trial for future nanocomposite developments

Epoxy adhesives are prone to brittle failure and thermal degradation. Nanotechnology allows for developing advanced epoxy adhesives, but attempt to design high-performance epoxy adhesives must be made by starting inexpensive trials in micron scales by the use of recycled and waste materials. Phenolic resin, recycled tire powder, and alumina microfillers were systematically mixed here as epoxy toughening agent and modulus/strength modifier, respectively. Incorporation of phenolic resin to epoxy compensated for low thermal stability. Taguchi experimental design was used to study the main effects of waste tire powder, alumina microparticles, and phenolic resin contents on tensile, single-lap joint and thermogravimetric properties of epoxy adhesive. The results suggest that addition of 40 wt. % alumina microparticles, 15 wt. % recycled tire powder, and 30 wt. % phenolic resin to epoxy led to a drastic rise of ca. 80% in the lap shear strength with respect to the neat epoxy. Microscopic analyses unraveled blocking mechanism for cracking, as evidenced by a deviation in crack growth pathway at the vicinity of alumina microparticles. A considerable increase of ca. 34 degrees C in degradation peak temperature of epoxy was also noticeable. The outcome of this work enlightened future perspective on nanostructured epoxy adhesives.