Incorporation of particles into the bulk of expanded polystyrene foam using physical vapour deposition technologies

Abstract

Expanded polystyrene foam (EPS) is used for various applications because of its significant properties (low weight, low cost, good thermal insulation, etc.). However, some of EPS characteristics should be improved. Because of this, additional materials are incorporated into polystyrene. This article presents the results of particles incorporation into EPS bulk using physical vapour deposition (PVD). TiO₂ was used as an additional material, which was incorporated into EPS foam. Non-expanded polystyrene beads were used as a  substrate. These beads were treated with argon plasma in order to achieve better surface adhesion. Plasma was generated at 1 × 10^–1 mbar pressure using a pulsed DC power source (frequency 20 kHz, voltage 400 V). Particles were deposited on the surface of non-expanded polystyrene beads. Titanium cathode was used as a primary material. The formation of particles was done using magnetron sputtering in reactive atmosphere. The mixture of argon and oxygen gas was used in order to form TiO₂ particles (argon 82%, oxygen 18%). Vacuum pressure was 6 × 10^–3 mbar during the particles formation process (power during deposition 240 W). Results showed that TiO₂ particles were formed on the surface of non-expanded polystyrene beads. These particles remained stable after expansion of beads and compounded in onepiece foam of EPS. Particles were distributed uniformly in all bulk of EPS and remained in place even after flame torch induced heat resistance experiments. The  modified EPS also showed photocatalytic activity during the bleaching of methylene blue (MB) aqueous solution under UV-B irradiation.