The effect of the composition of the phase behavior of polysulfone-poly(ethylene terephthalate) blends

Polysulfone-PET blends with different contents of PET were studied by differential scanning calorimetry. Glass transition temperature of polysulfone was shown to decrease with increasing the content of PET in the polymer blend to 15 wt %. In this concentration range, the melting temperature of PET was found to decrease with decreasing the content of PET in the PET-polysulfone blend. Variations in glass transition temperatures of polysulfone were well described by the Fox equation developed for compatible polymers, whereas variations in melting temperatures were described by the Nishi-Wang equation for polymer blends with the negative miscibility parameter. Experimental DSC and electron microscopic data indicated the development of a homogeneous amorphous phase in the polymer blends containing less than 15 wt % of the PET component.