Dielectric relaxation dynamics of Al/epoxy micro-composites

• Broadband dielectric spectroscopy study with wide temperature and frequency range.
• Detailed dielectric properties studies like dielectric permittivity are included.
• Relaxation processes fully explain the composites' dynamic dielectric phenomenon.

The dynamic dielectric properties of the Al/epoxy composites were investigated by means of broadband dielectric spectroscopy spectrometer with the frequency range 1–107 Hz at the temperature of −20–200 °C. Three relaxation processes are detected in the dielectric spectra as a function of temperature and frequency: (1) Maxwell interfacial polarization (IP) at low frequencies and high temperatures; (2) a primary α-relaxation process near Tg at the middle frequencies; and (3) Intermediate dipolar effect (IDE) relaxation at high frequencies above −20 °C. The dynamics of all the recorded processes include contributions from both polymer and the inorganic reinforcing phases. The analyses of loss tangent and electric modulus spectrum of the composites indicate that the chain segmental dynamics of the polymer are accompanied by the absorption of energy given to the system. Finally, the alternating current (AC) conductivity spectra support the hopping type of conduction in the composites and the ionic conduction relaxation processes are observed also.