Based on the consideration of polyvinyl chloride (PVC) as a combination of fluctuation structural elements with finite lifetime, the specificity of the composite behaviour in the temperature range 298 K $\leq T \leq$ ($T_{\textrm{c}}$ + 10) K is investigated. As shown, the maintenance of nanodispersed copper and nichrome, obtained by physically-chemical and/or electrical explosion of the conductor methods in the amount from 0 to 5.0% vol., in the PVC system leads to significant changes in density ($\rho$) and specific volume ($V$), which are important structural and thermodynamic characteristics of the material. The quantitative interrelation between $\rho$, $V$, $T$, mechanical (elastic modulus, coefficient of compressibility) and thermal (entropy, thermodestruction, heat capacity, anharmonicity factor) properties of a composite is established. Using the equation of the state of a PVC system, obtained on the basis of the potentials of the inter- and intramolecular interaction, the formation of the boundary layer and its influence on the defect structure of the material are analysed with taking into account the $\rho$ and $T$ changes.