Evidence for molecular orientation and residual charge in the electrospinning of poly(butylene terephthalate) nanofibers

Poly(butylene terephthalate) electrospun fibers were analyzed by a thermally stimulated current (TSC) technique. In the absence of an electric field, a spontaneous current was released near the glass transition, indicating a dipole relaxation process. A monotonic increase in current generated by dissipation of residual was observed with increasing temperature below the melting point. A peak in the charge dissipation current near the melting point indicates that a substantial amount of residual charge is trapped within or at the interface of the crystalline phase. Molecular orientation was also probed by birefringence analysis. Electrospun fibers showed a high level of birefringence, which extinguished upon melting.