ABSTRACT

Temperature-dependent dielectric relaxation studies of different viscosity grade Polyvinylpyrrolidones (PVP), PVP K-15, PVP K-30 and PVP K-90 having molecular weight 10,000 gmol⁻¹, 40,000 gmol⁻¹ and 360,000 gmol⁻¹ respectively has been done in the frequency region 10 MHz to 50 GHz using Time domain reflectometry (TDR) technique. The frequency-dependent complex dielectric permittivity spectra have been explored by the Havriliak-Negami expression and is explained by the single relaxation model. The PVP molar concentration comprises the concentration domain of 0.0017 ≤ c/M ≤ 0.0176 for PVP-water system. The values of static dielectric constant (ε₀), relaxation time (τ) and the empirical parameter (β) have been determined using non-linear least squares fit method along with the thermodynamic properties (activation enthalpy, entropy and free energy) of aqueous solutions of polymers.

摘要

已经完成了分子量分别为 10,000 gmol ^-1、40,000 gmol ^-1和 360,000 gmol ^-1的不同粘度等级的聚乙烯吡咯烷酮 (PVP)、PVP K-15、PVP K-30 和 PVP K-90 的温度依赖性介电弛豫研究使用时域反射计 (TDR) 技术在 10 MHz 至 50 GHz 的频率范围内。频率相关的复介电常数谱已通过 Havriliak-Negami 表达式进行了探索，并由单弛豫模型进行了解释。对于 PVP-水体系，PVP 摩尔浓度包括 0.0017 ≤ c/M ≤ 0.0176 的浓度域。静态介电常数 (ε ₀)、弛豫时间 (τ) 和经验参数 (β) 已使用非线性最小二乘拟合方法以及聚合物水溶液的热力学性质（活化焓、熵和自由能）确定。