The regularities of expanded polystyrene (EPS) waste modified by polyvinylpyrrolidone (PVP) with the simultaneous gas release in various solvents were revealed. The upper sorption limit depends on the nature of the solvent, the concentration and molecular mass of the PVP, the temperature of the process, and the apparent density of the EPS. It was established that the sorption limit of PVP increases with increasing of its concentration in the system and decreases with molecular mass increasing. Based on XRD and FTIR analyses, it was determined that materials based on polyamide 6 and EPS modified by PVP have an increased crystallinity degree by 10-15%, a smaller average crystallite size and higher technological compatibility. The addition of PVP-modified EPS contributes to the increase of the yield strength of polyamide 6 by about 5%-10%. The increase of the Vicat softening point by 5-8 K and the surface hardness by 25-30 MPa of materials based on polyamide 6 and modified polystyrene was investigated. It is caused by the redistribution of intermolecular bonds between the components of the blend under by the effect of a uniformly distributed PVP in the EPS resulting in increased compatibility between the components and the compacted structure. POLYM. ENG. SCI., 2020. (c) 2020 Society of Plastics Engineers