Several compositionally different poly(ethylene terephthalate-co-1,4-phenylene bisacrylate) (PETPBA) copolymers were melt spun into fibers. The resulting fibers were subjected to UV irradiation to induce crosslinking. Evidence of crosslinking was obtained from FTIR, solid-state C-13-NMR, thermal analysis, and solubility. Irradiation of the fiber results in an increased glass-transition temperature, reduced thermal shrinkage, and enhanced modulus retention at elevated temperature. (C) 2003 Wiley Periodicals, Inc.