Graphitization of highly crystalline cellulose

Native cellulose samples of high crystallinity were pyrolyzed in nitrogen and the structure of the resulting carbon was studied by X-ray diffraction and transmission electron microscopy. All samples became amorphous carbon after treatment at 500 degreesC and were then graphitized at 2000 degreesC. All the graphite samples showed strong 002 reflections in X-ray diffraction, but only the ex-Halocynthia sample gave 100 and 101 reflections showing the presence of three-dimensional order. The order of crystallinity was Halocynthia (tunicin)similar to Cladophora (alga)>Acetobacter>ramie (linen). Electron microscopy showed that the graphite samples, except fur the ex-ramie, contained long microfibrillar units, indicating chat certain portions of the cellulose microfibrils were graphitized while retaining their morphology. (C) 2001 Elsevier Science Ltd. All rights reserved.