MISCIBILITY OF POLY(ETHYLENE TEREPHTHALATE) POLY(ETHYLENE 2,6-NAPHTHALATE) BLENDS BY TRANSESTERIFICATION/

The effects of transesterification on the miscibility of poly(ethylene terephthalate)/poly(ethylene 2,6-naphthalate) were studied. Blends we re obtained by solution precipitation at room temperature to avoid tra nsesterification during blend preparation. The physical blends and tra nsesterified products were analyzed by wide-angle x-ray scattering, di fferential scanning calorimetry, and nuclear magnetic resonance spectr oscopy. It was found that the physical blends are immiscible and when the extent of transesterification reaches 50% of the completely random ized state, independent of blend composition, the blends are not cryst allizable and show a single glass transition temperature between those of starting polymers. The interchange reactions were significantly in fluenced by annealing temperature and time but negligibly by blend com position. (C) 1996 John Wiley & Sons, Inc.