Comparative Study of Matrix Fiber Adhesion of Tannin/Vegetable Fiber, Tannin/Synthetic Fiber and Epoxy Composite Materials

Abstract

This paper aims to compare the fiber-matrix adhesion of epoxy/kenaf and tannin/kenaf composite materials. Pull-out tests were performed to assess the shear strength at the fiber-matrix interface. The observations are correlated with statistical analyses. The results showed that the shear strength at the fiber-matrix interface was significantly higher for kenaf fibers treated with 0.5 M sodium hydroxide (NaOH) and coupled with epoxide (0.1390 N/mm²) compared to the same fibers treated and coupled with a tannin-based vegetable matrix (0.0903 N/mm²). However, this treatment caused a slight reduction in the tensile strength of the fibers. The surface of the treated kenaf fibers is very clean; the disappearance of impurities such as wax and oil led to improved molecular cohesion on the surface of the treated kenaf fibers, suggesting enhanced fiber-matrix adhesion. In fact, the absorption and dispersion energies on the fiber surface increased with the sodium hydroxide treatment and alkalization.