EFFECTS OF CHEMICAL TREATMENTS AND HEATING ON THE CRYSTALLINITY OF CELLULOSES AND THEIR IMPLICATIONS FOR EVALUATING THE EFFECT OF CRYSTALLINITY ON CELLULOSE BIODEGRADATION

Chemical treatments similar to those routinely used to extract cellulo se from plant biomass caused significant increases in the relative cry stallinity index (RCI) of Sigmacell 100 (a commercial cellulose of mod erate crystallinity), as measured by x-ray powder diffraction in both the reflectance and transmittance modes. In general, the largest incre ases in RCI were observed following higher (rather than lower) tempera ture treatments. Substantial increases in crystallinity were also obse rved upon resuspension in water prior to drying, with higher temperatu res again resulting in the greatest increases in RCI. Measurement of t he RCIs of wetted Sigmacell 100 samples by acid hydrolysis kinetics re vealed that most of the increased crystallinity occurred rapidly upon contact with water. In contrast to Sigmacell 100, a cellulose of highe r initial crystallinity (the microcrystalline cellulose Sigmacell 50) showed little change in crystallinity following the above treatments. The results provide a partial explanation for the inconsistent relatio nships reported between cellulose crystallinity and cellulose biodegra dation. (C) 1995 John Wiley & Sons, Inc.