Effect of bio-inspired surface texture on the resistance of 3D-printed polycarbonate bonded joints

Abstract

Surface preparation before adhesive bonding is crucial to improve the resistance and durability of the joint by altering the surface properties of the adherend. The purpose of surface treatment is to clean the surface from contaminants, activate the adherend surface and create an optimal surface structure to promote adhesion mechanisms. In that context, this work aims to investigate the influence of substrate surface texturing on the resistance of adhesive joints. Two bio-inspired surface textures were investigated, Fish scale (FS) and Tree frog (TF). Polycarbonate (PC) specimens with different surface patterns were manufactured using the fused deposition modelling process. Surface morphology, such as pattern dimension (shape and depth), surface roughness (Ra), and wettability, were used to characterise the substrates. The influence of these texture patterns on the shear strength of adhesively bonded joints was evaluated through the standardised block shear test method ASTM D4501-01. Moreover, the shear strength of the structured joints was compared to the results from bonding with polished surfaces (surfaces abraded with 80, 600 and 1000 grit paper), and with as-printed surfaces. The results revealed that the FS and TF surface textures enhanced the shear strength by 242% and 283% compared to the adhesive joints with polished surfaces. It was also shown that the variation in depth of the bio-inspired surface texture has no significant impact on the joint strength. Failure analysis demonstrated that the fracture mode of bonded joints with polished surfaces was the adhesive failure while mixed failure (cohesive and adhesive) characterises the as-printed, TF and FS surfaces. Worthy results are obtained rising the effectiveness of surface texture for the PC's bonded joints. Graphical Abstract [Formula: see text] This is a graphical representation of the abstract.