Tripling thermoplastic adhesive tape shear fatigue lifetime by decorating the adhesive–carrier interface with tailored sacrificial defects

Abstract

Thermoplastic adhesive tapes are widely used in nonstructural applications such as automotive and medical industries, where fast bonding is needed with relatively good adhesion. In medical applications, the possibility of modifying the adhesive or carrier materials to adjust the toughness of the tape is very limited because of bio–compatibility constraints. In this work, the properties of the adhesive joints are enhanced without changing either the adhesive or carrier materials but by only decorating the adhesive– carrier interface with tailored defects, where the toughness and strength can be tailored depending on the size, distribution and fractional area of defects. The results show that the advanced tapes can sustain up to 83 % and 210 % larger lap-shear strength and fail-ure initiation strain, respectively, compared to conventional tapes. This improvement is attributed to the ability of the defects to redistribute the stresses at the adhesive–carrier interface during loading than localizing them at the adhesive–substrate interface, which happens in the case of conventional tapes. This delays the damage initiation. Even after damage is initiated at the edges of the adhesive–substrate interface, formation of adhe-sive ligaments starts, that sustain the load and delay the final failure. Furthermore, the proposed advanced tape has a fatigue lifetime of more than three times longer than that of conventional tapes, which is promising for enhancing the treatment of human joints.