Abstract
Forty wt % blend of general purpose polystyrene resin with polybutadiene rubber is very hard and shows poor processability, when it is prepared by open mill under ordinary conditions.
However, this hard compound was found to be softened and show excellent processability when it is remilled by open mill at a surface temperature of 90°C.
The effects of blend ratio and remilling temperature were studied with the following results obtained. The softening is observed clearly when the blend is composed of 20 to 60 wt % of general purpose polystyrene resin and the surface temperature of remilling roll is below 120 °C. This phenomenon is caused by socalled phase transition of general purpose polystyrene resin from continuous phase to non-continuous one.
