A novel quaternary blend system of poly(ethylene terephthalate), poly(trimethylene terephthalate), poly(butylene terephthalate), and poly(ether imide)

A quaternary blend system composed of three low-T_g semi-crystalline aryl-polyesters namely, [poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), and poly(butylene terephthalate) (PBT)] and an amorphous high-T_g poly(ether imide) (PEI) was prepared and investigated using thermal and morphology characterization techniques. This study, for the first time, demonstrated miscibility and phase behavior of a quaternary blend comprising four different polymers. A single and composition-dependent T_g was found for each of all quaternary blend samples. In addition, various thermal transition characteristics, single and composition-dependent T_c,c, increasingly suppressed ΔH_c,c at higher PEI contents, are also indication of phase miscibility of the quaternary blend. SEM morphology characterization (3000X) revealed no discernible domains and homogeneous phase morphology in the quaternary blends was also substantiated using optical and scanning electron microscopy results.