Improving the interfacial properties of para aramid fibers by surface treatment via plasma jet method in atmospheric pressure

Various methods have been used by the researchers in order to improve the interfacial adhesion of para aramid fibers. In the present research, poly para-phenylene terephthalamide (PPTA) fibers were treated by an innovative method through the utilization of plasma jet in atmospheric pressure using a mixture of oxygen and argon as inlet gases. The effect of the volume ratio of O2/Ar and the treatment time were investigated on the interfacial properties of the fibers via SEM, AFM, ATR-FTIR analyses, and moisture sorption as well as the mechanical tests. SEM images demonstrated significant effect on the surface morphology of the fibers. In addition, ATR-FTIR spectra resulted in the creation of COOH, NH2, and OH groups on the surface of fibers. The increase in the surface functionality led to an improvement in the surface adhesion of the fibers, as observed from the pull-out tests (a maximum of 31% improvement) and moisture sorption tests (a maximum of 54% improvement). According to the results of the tensile and pull-out tests via the design expert software, the optimum condition predicted that using atmospheric pressure plasma jet employing O2/Ar volume ratio of 45.54/54.46% for 20 min results the best adhesion between the fibers and resin.