Surface Modification Of Ultra High Modulus Polyethylene Fibers By An Atmospheric Pressure Plasma Jet

Ultra high modulus polyethylene (UHMPE) fibers were treated by an atmospheric pressure plasma jet (APPJ) with 13.56 MHz radio frequency power and helium feed gas to improve adhesion with epoxy matrix. The adhesion properties of the activated surfaces were evaluated by microbond tests. The results were correlated with the surface properties that were investigated by XPS, SEM and contact angle measurements. The diffusion of fluorescein into plasma treated UHMPE fibers have been studied for the first time by laser scanning confocal microscopy (LSCM). In addition the influence of operational parameters of the plasma treatment including output power and treatment temperature was studied. XPS analysis showed an increase in the oxygen content. As a result, the The microbond test showed that the interfacial shear strength increased significantly (57% ~ 139%) after plasma treatment for all groups. Meanwhile, the contact angle exhibited a characteristic increase in wettability which is attributed to the polar groups introduced by plasma treatment as characterized by XPS analysis. The single fiber tensile strength decreased 10% after the plasma treatments. While SEM analysis did not show significant surface morphological changes at a magnification of 3000× after the plasma treatments because of the mild plasma conditions provided by APPJ.