Comparison of wettability and capillary effect evaluated by different characterizing methods

The objective of this paper is to compare the capillary pressures and contact angles obtained by different characterizations including Wihelmy plate, droplet spreading, wicking, and infiltration experiments driven by air pressure or vacuum, respectively. Effects of temperature and fiber contents have been analyzed. The resultant contact angles and capillary pressures are quite different from the five measurements. Wihelmy plate method provides the quasi-static capillary pressure while in droplet spreading and wicking experiments capillary flow and spreading flow happen which depend closely on the fiber arrangement and resin viscosity. In addition, capillary pressures in axial impregnation show the same increasing tendency with the increase of fiber content. And the differences are found to be caused by the dynamic features of capillary pressure, especially for the infiltration flow driven by vacuum, which acts as a special drag force.