Graphitization of highly crystalline cellulose

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