磷酸活化粘胶基活性炭纤维的碳化活化机理

采用热重分析仪、红外光谱仪、X－射线衍射仪、核磁共振仪、X－射线光电子能谱仪及吸附仪等手段对磷酸浸渍粘胶纤维的碳化活性过程进行研究，实验结果表明：磷酸促进纤维素脱水，加上磷酸的阻及交联作用降低了纤维的大量裂解和碎片的逸散，使纤维的碳残留率提高。纤维素与浸渍的磷酸部分生成磷酸酯键，但它们在160℃以上逐渐分解。纤维上残留少量偏磷酸类化合物。同时纤维素基体脱水生成羰基和共轭双键，之后不断芳构化堆叠成为类石墨微晶。磷酸致孔的机理主要是磷酸珠粒的阻碍造成类石墨微晶发展不完善，堆叠时发生扭曲或形成缺陷。磷与纤维分子的酯化对微孔的生成有影响。

THE CARBONIZATION-ACTIVATION MECHANISM OF VISCOSE-FIBER BASED ACTIVATED CARBON FIBER ACTIVATED WITH PHOSPHORIC ACID

By means of TG, FTIR, XRD, NMR, XPS, micropore analyzer and other anal ytical methods, the carbonization-activation mechanism of viscose-fiber based ac tivated carbon fiber activated with phosphoric acid was investigated. It is conc luded that the enhancement dehydration, the inflaming retardancy and cross linka ge of phosphoric acid used for viscose fiber reduce the decomposition of the pre cursor and inhibit the evolution of volatile fragments, thus increase the yield of carbon. The cellulose fiber is partially reacted with phosphoric acid impregn ated to form phosphonate ester at first. However, the phosphonate ester is decom posed over 160 oC. Small amount of metaphosphoric acid is produced and remained on fiber. At the same time, the cellulose matrix is dehydrated to produce carbon yl group and conjugated olefinic bond, and then transfers into aromatic rings an d graphite-like micro-crystal gradually. The porosity formation is assumed to be that the inhibition of phosphoric acid particles in cellulose matrix causes the growth mistake of graphite-link crystal face, results the twist of carbon layer s and produces porosity in carbon skeleton. The esterification of phosphoric aci d with cellulose affects the formation of micro pores on viscose-fiber based act ivated carbon fiber.