Surface chemical modification of natural cellulose fibers

Simple esterification and etherification reactions were applied to steam-ex ploded Flax (Linum usitatissimum) with the aim of changing the surface prop erties through modification of fiber surface chemistry. Native and chemical ly modified cellulose fibers were characterized in terms of thermal stabili ty, surface chemistry, morphology, and crystal structure. Independent of th e substituent nature, chemically modified fibers exhibited a thermal stabil ity comparable to that of native cellulose. Introduction of the desired che mical groups at the fiber surface was demonstrated by TOF-SIMS analysis, wh ereas FTIR showed that the substitution reaction involved only a small frac tion of the cellulose hydroxyls. No change of the native crystalline struct ure of cellulose fibers was caused by chemical modification, except in the case where ether substitution was carried out in water-isopropanol medium. Cellulose fibers with unchanged structure and morphology and carrying at th e surface the desired chemical groups were obtained for reinforcing applica tions in polymer composites. (C) 2002 John Wiley & Sons, Inc.