Dielectric analysis of the interfacial polarization of alkali treated woven flax fibers reinforced epoxy composites

• Dielectric measurements were performed on flax fibers reinforced epoxy composites.
• Alkali treatments of the reinforcement were taken into account in adhesion analysis.
• Interfacial polarization analysis revealed an improvement of the adhesion.
• The best adhesion was obtained by the leaching treatment.

Dielectric measurements were performed on alkali treated flax fibers reinforced epoxy composites in the frequency range 0.1 Hz–1 MHz and the temperature range 40–170 °C. Two common dielectric relaxations were observed for all composites. The first one appearing at low temperatures was attributed to the water dipoles polarization due to the hydrophilic character of flax fibers. The second one observed at high temperatures was identified to the interfacial polarization. Analysis of this latter using the Havriliak–Negami model showed an improvement of the fibers/matrix adhesion by these alkali treatments. The best adhesion was obtained by the leaching treatment.