Analysis of the effect of size, amount and surface treatment on the tensile strain of a brittle adhesive reinforced with micro cork particles

Nowadays, structural adhesives are increasingly being used for new applications, replacing conventional bonding methods. Epoxy resins are the most common structural adhesives used due to their suitable mechanical, thermal and chemical properties, despite their low ductility. In the past decades, several researchers have found it crucial to reverse these properties and find new ways to increase the ductility of these adhesives. The inclusion of particles (nano or micro) is an effective method to improve ductility of structural adhesives. In the present study, natural micro particles of cork are used with the objective of increasing the ductility of a brittle epoxy adhesive. The concept is for the cork particles to act like as a crack stopper leading to more energy absorption. The influence of the cork particle size, amount and the presence of a surface treatment were studied. The maximum strain of the adhesive was assessed through tensile tests. A Taguchi design experiments was used to understand the influence of each parameter under study (amount, size and presence of surface treatment) and their interaction. Through this research it was possible to settle that cork can improve ductility and cork amount, size and the use of plasma surface treatment have influence on the mechanical properties.