Estimation of effective Debye temperature of polymeric solutions at 303.15 K based on quasi-crystalline model

Based on the quasi-crystalline model of liquids, effective Debye temperature (θ _D )of six binary polymeric solutions has been computed at 303.15 K using ultrasound velocity and density data. The binary systems studied herein are polypropylene glycol (PPG) 400 + ethanol, PPG-400 + 1-propanol, and PPG-400 + 1-butanol, polyethylene glycol (PEG) 200 + methyl acrylate, PEG 200 + ethyl acrylate, and PEG-200 + n-butyl acrylate. To understand the anharmonic and quasi crystalline behaviour of these systems, several other parameters such as excess Debye temperature, diffusion constant, latent heat of melting, Debye frequency, pseudo-Grüneisen parameter (Γ), Bayer's parameter (B/A) and Lennard-Jones potential repulsive term exponent have also been determined. Excess Debye temperature values are fitted with the Redlich-Kister polynomial equation. From the knowledge of R-K coefficients, the physico-chemical characteristics of the binary mixtures are analyzed and discussed in terms of molecular interactions leading to the existence of quasi-crystalline structures in the systems under study. The effect of the variation of the alkyl chain of alkanols on the properties of PPG-400 + n-alkanol binary systems has been investigated. In addition, the effect of alkyl chain variation of acrylates on the properties of PEG-200 + alkyl acrylate binary systems has also been studied. The analysis of the obtained results points out that the effective Debye temperature and other related parameters can be successfully estimated for these binary polymeric solutions using quasi-crystalline model. The present investigation provides significant information about the existence of quasi crystalline structures and the related structural changes occurring in these polymer solutions with variation of the type and concentration of a solute.