Influence of adsorbed moisture on the properties of cyanate ester/BaTiO3 composites

The effect of moisture adsorbed on BaTiO3 on the properties of cyanate ester (CE)/BaTiO3 dielectric composites is examined using undried and dried BaTiO3 particles. The influence of moisture on the dielectric constant, thermal stability, dynamic mechanical properties, flexural behavior and micro morphology of the composites is investigated. Dielectric constant (ε) and dielectric loss (tan δ) of composites with the dried BaTiO3 are both higher than composites manufactured with undried filler at the same frequency. The dielectric properties of the dried system are stable over a broader temperature range than the undried composites. Adsorbed moisture causes the initial decomposition temperature and the maximum degradation temperature of the composite to decrease by 27 °C and 15 °C, respectively. By removing the moisture from BaTiO3, the CE/BaTiO3 composite exhibits a lower modulus (E′), higher strength, higher flexural elongation and a dramatically increased glass transition temperature (Tg).