Dielectric relaxation anomalies in polyacrylic acid and their relationship with 'critical' points of water

The dielectric properties of polyacrylic acid were studied using dielectric spectroscopy method in the frequency and temperature ranges 0.2 Hz–2 MHz and 2–70°C (at heating), respectively. Thermogravimetric analysis and differential scanning calorimetry were also employed at 25–250°C. A linear dielectric dispersion has been observed at low frequencies. Analysis of electrical modulus showed that the main relaxation process is characterized by non-Debye relaxation time spectrum. The observed anomalies of dielectric properties (conductivity, electrical modulus, dielectric permittivity) are probably related to the presence of water in the sample.