Influence of cold plasma treatment parameters on the mechanical properties of polyamide homogeneous bonded joints

This study reports a systematic investigation of the effects of various cold plasma treatment parameters on adhesion characteristics of two polyamide substrates. Polyamide 6 and polyamide 6.6 specimens were treated with a low pressure radio-frequency discharge plasma using different treatment time, power inputs and working gas (air, argon and oxygen). Contact angle measurements with sessile drop technique were carried out for estimation of surface wettability, as well as surface roughness evaluation and X-ray Photoelectron Spectroscopy (XPS) analysis. Then, untreated samples and cold plasma treated samples were adhesively bonded together to form overlap joints. Single lap shear tensile testing of these adhesively bonded joints was performed to investigate the effect of different surface treatments on the joint strength. The experimental results show that the optimized plasma process may remarkably increase wettability properties of polyamide surface and shear strength of the bonded joints.