Debye temperatures and nanostructuring of polyurethane auxetics

Abstract

Based on experimental values of longitudinal and transverse ultrasonic wave propagation velocities and surface Rayleigh wave velocities were calculated phonon energies and Debye limiting frequencies and temperatures were determined of metal-filled polyurethane auxetics samples. Modeling the structural formations of such systems and obtaining the value of the lattice and Grüneisen acoustic parameter made it possible to find the root-mean-square displacement of the atomic groups of the macromolecule, as well as the limits of forced elasticity, shear deformation, and deformation of the interstructural bond. The relationship between Debye frequencies (temperatures) and Poisson's ratio, Grüneisen parameter, was established. A quantum-mechanical approach to the movement of electrons, atomic groups of macromolecules, thermal and sound phonons made it possible to estimate the size of nanoformations in the composition. The theoretical values of Poisson's ratio obtained based on models of polymer auxetics and processes of propagation of ultrasonic waves in such systems are analyzed.

Keywords

• polymer auxetic
• longitudinal, transverse and surface waves
• propagation velocity
• poisson's ratio
• temperatures and debye frequencies
• root mean square deviation
• nanostructuredness