Testing and evaluation of adhesive bonded joints of unreinforced and glass fiber–reinforced polyoxymethylene treated with low-pressure plasma

Abstract

The effect of surface treatment of polyoxymethylene (POM) using low-pressure plasma (LPP) on its adhesive bonding was investigated. Three different types of adhesives were used. Examinations of single lap shear, scanning electron microscopy, contact angle measurements, and energy dispersive X-ray analysis were carried out. The results showed that the adhesion strength was apparently enhanced when treating surfaces by LPP using argon or oxygen plasma which increased with the treatment time. This increase was also dependent on the adhesive type. Moreover, glass fiber–reinforced POM showed better adhesion strength compared to that of unreinforced POM. An increase in the surface free energy exceeding 50 mN/m was observed after 600-s treatment time compared to untreated samples (39 mN/m), where the increase in polar component was more predominant. Surface topography observations showed a significant increase in the surface roughness with increasing the treatment time, mainly when using oxygen plasma. Finally, an increase in polarity and wettability due to changes in the chemical composition of the surface was also reported.