Fig. 3.
SEM images of the prepared PAN nanofibers under different working temperatures. a F1, ambient temperature (20 °C), b F2, 40 °C, c F3, 60 °C, and d F4, 80 °C. The upper-right insets show enlarged images of the corresponding PAN fibers
SEM images of the prepared PAN nanofibers under different working temperatures. a F1, ambient temperature (20 °C), b F2, 40 °C, c F3, 60 °C, and d F4, 80 °C. The upper-right insets show enlarged images of the corresponding PAN fibers