Liquid/Fiber and Solidified-Liquid/Fiber Contact Angles Compared

Abstract

Data are presented showing that the contact angle formed by a liquid resin droplet placed on a single fiber is comparable with a receding contact angle. This was ascertained by comparing Wilhelmy wetting force measurements with liquid droplet profile analysis. Subsequently, the latter analysis was carried out on cured (solidified) epoxy droplets placed on Kevlar fibers. Dimensional changes observed after curing showed that the contact angles of the solid droplets were smaller than that for liquid resin: however, the presence of residual stresses because of adhesion to the fiber may make droplet profile analysis inaccurate for obtaining an equilibrium receding contact angle for the solid droplets.

Key Words:

• Wettability
• contact angle
• interface
• fiber
• resin