Surface energy of aramid fiber/pulp and their sheets properties

The surface contact angles of several meta-aramid fibers and meta-aramid pulps as well as their sheets were measured，and the surface energy of aramid fiber，aramid pulp and sheet was determined according to the harmonic mean-based Wu equation. The relationship between the surface energy and sheet properties in sheet processing was discussed according to the surface energy as well as the interfacial tension and work of adhesion of aramid fibers and pulps. The results show that the surface energy of aramid fibers and pulps is in the range of 35～45 mJ·m^-2，the surface energy of fibers is slightly higher than that of pulps，the polar component of surface energy is larger than the dispersion one，and the wettability and work of adhesion are enhanced with increase of the surface energy of aramid fibers and pulps，when water and glycol are employed as the testing liquids. The surface energy of aramid sheet decreases during hot-press process，and compared to Nomex sheet，the surface energy of self-made aramid sheet decreases sharply after hot-press process. The better the matching of polar component with dispersion component，the smaller the difference of surface energy and the smaller the interfacial tension，the stronger the adhesion between fibers and pulp with the improved strength of aramid sheet.