Miscibility, melting, and crystallization of poly(trimethylene terephthalate)/poly(ether imide) blends

Abstract

Miscibility, melting, and crystallization behaviors of solution-blended poly trimethylene terephthalate) (PTT)/poly(ether imide) (PEI) blends ha,e been investigated using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and polarized light microscopy (PLM). These blends show a single and composition-dependent glass transition temperatures over the entire composition range, implying that these blends are fully miscible in the amorphous region. The enthalpy of the middle endotherm melting of the primary crystallization decreases with increasing PEI content in the blend. Recrystallization of PTT during heating scan in DSC is either retarded or fully inhibited by the presence of PEI. In nonisothermal crystallization, the depression of crystallization temperature of PTT also depends on the blend composition and cooling rate; the presence of PEI decreases the PTT segments migrating to the crystallite-melt interface, The effects of temperature and PEI content on the spherulite growth rate of PTT were evaluated by PLM. The spherulite growth rate decreases with the, increase of the PEI content, implying that it is a thermodynamically dominant process. Both thermodynamic and kinetic factors cause total inhibition of PTT crystallization at higher PEI content in the blend. (C) 2002 John Wiley Sons, Inc.