Contact angle of epoxy resin measured by capillary impregnation and the wilhelmy technique

Good wetting plays an important role in improving the degree of adhesion at interfaces between fibres and matrices in composites. The contact angle of an epoxy resin, as a widely used polymeric matrix, was studied by impregnation in single glass capillaries at the manufacturing temperature of the composites. In order to obtain the net wicking mass for capillary experiments, the meniscus force at the bottom of the glass tube was investigated, with the help of the Wilhelmy technique, conducted by using glass sticks with various diameters. Results show that the contact angles resulting from equilibrium using both capillary impregnation and the Wilhelmy experiment are consistent, which indicates the reliability of the practical evaluation of the effect of the meniscus on the penetration mass. The contact angle of this epoxy resin was approximately 60° resulting from the equilibrium of the capillary impregnation and the Wilhelmy experiments at 80°C.