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.