Choosing the Impregnants by Thermogravimetric Analysis for Preparing Rayon-Based Carbon Fibers

The pyrolytic process in preparing rayon into activated carbon fiber was studied by thermogravimetric analyses (TGA) and differential thermal gravimetry (DTG). For the promotion of the pyrolytic reaction and increment of carbonization yield, impregnants including phosphoric acid (PA) and its three ammonium salts, as well as the ammonium sulfate (AS), are added respectively for best resultant both air and nitrogen atmospheric environments. The TGA and DTG curves for different cases— various combinations of impregnants and environment—are examined and some features from the curves are selected to characterize each curve more efficiently. The influence of the impregnants as well as the atmospheric conditions are investigated and some useful conclusions are drawn, which are deemed critical in quality control of the resultant activated carbon fibers.