EFFECTS OF CHEMICAL TREATMENTS AND HEATING ON THE CRYSTALLINITY OF CELLULOSES AND THEIR IMPLICATIONS FOR EVALUATING THE EFFECT OF CRYSTALLINITY ON CELLULOSE BIODEGRADATION
Pj. Weimer et al., EFFECTS OF CHEMICAL TREATMENTS AND HEATING ON THE CRYSTALLINITY OF CELLULOSES AND THEIR IMPLICATIONS FOR EVALUATING THE EFFECT OF CRYSTALLINITY ON CELLULOSE BIODEGRADATION, Biotechnology and bioengineering, 48(2), 1995, pp. 169-178
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.