Blends of SBS triblock copolymer with poly(2,6-dimethyl-1,4-phenylene oxide)/polystyrene mixture

Blends of styrene–butadiene–styrene (SBS) or styrene– ethylene/1-butene–styrene (SEBS) triblock copolymers with a commercial mixture of polystyrene (PS) and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) were prepared in the melt at different temperatures according to the chemical kind of the copolymer. Although solution-cast SBS/PPO and SBS/PS blends were already known in the literature, a general and systematic study of the miscibility of the PS/PPO blend with a styrene-based triblock copolymer in the melt was still missing. The thermal and mechanical behavior of SBS/(PPO/PS) blends was investigated by means of DSC and dynamic thermomechanical analysis (DMTA). The results were then compared to analogous SEBS/(PPO/PS) blends, for which the presence of a saturated ole.nic block allowed processing at higher temperatures (220°C instead of 180°C). All the blends were further characterized by SEM and TGA to tentatively relate the observed properties with the blends’ morphology and degradation temperature.