Surface modification of aramid fiber by plasma induced vapor phase graft polymerization of acrylic acid. I. Influence of plasma conditions

Plasma induced vapor phase graft polymerization (PIVPGP) method was applied to modify aramid fiber surface. In this study, aramid fibers were pretreated under various plasma conditions such as different treatment times, output powers and working gases to see how these plasma processing parameters influenced the PIVPGP of acrylic acid (AA) on aramid fiber surface and its surface structure and properties. The analysis results of atomic force microscope (AFM) and X-ray photoelectron spectroscope (XPS) showed the increase of surface roughness and the introduction of O=C OH, which confirmed that the PIVPGP of AA on aramid fiber surface was achieved. The contact angle and interfacial shear strength (IFSS) of the aramid fibers modified by PIVPGP of AA prominently decreased and increased, respectively, indicating the obvious improvements of surface wettability and adhesion between aramid fiber and matrix. The surface modification effects of aramid fiber by PIVPGP of AA firstly increased and then after 15 min slightly decreased with the increasing plasma treatment time, and but firstly increased and then after 300W nearly remained unchanged with the increasing output power, respectively. Among different working gases, Ar plasma occupied first place, O-2 plasma and N-2 plasma came second and third in the aspect of PIVPGP of AA on aramid fiber surface, respectively. It could be concluded that the PIVPGP of AA on aramid fiber surface could effectively improve surface wettability and adhesion. Plasma conditions had signally influence on the efficiency of PIVPGP of AA on aramid fiber surface and its surface structure and properties with the primary sequence of plasma treatment time, output power and working gas. Therefore adequate plasma processing parameters should be carefully selected for the optimum surface modification of aramid fiber by PIVPGP of AA. (C) 2015 Elsevier B.V. All rights reserved.