The glass transition temperatures of PS/PPO blends: Couchman volume-based equation and its verification

The glass transition temperatures (Tg) of PS/PPO blends with different compositions were studied under various pressures by means of a PVT-100 analyzer. A general relation of Tg and pressure of the PS/PPO system was deduced by fitting the experimental Tgʹs. Couchman volume-based equation was testified with the aid of those data. It was found that the experimental Tgʹs do not obey the Couchman equation of glass transition temperature based on thermodynamic theory. According to our studies, the major reason of the deviation is caused by the neglect of ΔVmix.