| 簡(jiǎn) 介： |
Lyocell/CNT composite fibers were pretreated with various catalysts in order to prepare carbon fibers. These catalysts included phosphoric acid (PA), urea (U), mixture of phosphoric acid and urea (PA/U) with different mole ratios, ammonium dihydrogen phosphate (ADP) and diammonium hydrogen phosphate (DHP). The carbon fibers were obtained
from those pretreated fibers by heat treating at 110℃, 150℃, 200℃ and 250℃ successively and carbonizing at 1000℃. The pyrolysis behavior of those pretreated fibers was investigated by thermogravimetry (TG) analysis. The results indicated that the pyrolysis of the pretreated fibers started at a lower temperature and the char yields increased dramatically. The mechanical properties of the untreated, heat treated and carbonized fibers were measured respectively. It was concluded that the diameter of the fibers decreased as the heat treatment temperature gradually rose. The tensile strength and elongation at break firstly decreased and then increased during heat treatment and carbonization. Compared with other catalysts, PA/U was the most appropriate one with an optimal mole ratio (P: N) of about 2:1, and the carbon fibers produced with this catalyst possessed a greater tensile strength. |
