Study of dielectric relaxation and thermodynamic behaviour in poly(propylene glycol) using Time Domain Reflectometry

► Static dielectric constant ε0 decreases with increasing chain length and temperature for PPG-425, 1000 & 2000. ► Dielectric relaxation strength Δε decreases with increasing degree of polymerization and temperature. ► Free energy of activation ΔFτ for the PPGs is found to be in the range of 4-5 kcal mol− 1. ► Enthalpy of activation ΔHτ for PPG-2000 is found less than that of PPG-425 & PPG-1000. ► Entropy of activation ΔSτ for PPG-2000 is found negative and positive for PPG-425 & PPG-1000.