Phase transformations in microcrystalline cellulose due to partial dissolution

Benoît J.C. Duchemin (1) , Roger H Newman (2) , Mark P Staiger (1)

1 University of Canterbury [Christchurch]
2 Scion - New Zealand Forest Research Institute

All-cellulose composites were prepared by partly dissolving microcrystalline cellulose (MCC) in an 8.0 wt% LiCl/DMAc solution, then regenerating the dissolved portion. Wide-angle X-ray scattering (WAXS) and solid-state 13 C NMR spectra were used to characterize molecular packing. The MCC was transformed to relatively slender crystal-lites of cellulose I in a matrix of paracrystalline and amorphous cellulose. Paracrystalline cellulose was distinguished from amorphous cellulose by a displaced and relatively narrow WAXS peak, by a 4 ppm displacement of the C-4 13 C NMR peak, and by values of T 2 (H) closer to those for crystalline cellulose than disordered polysaccharides. Cellulose II was not formed in any of the composites studied. The ratio of cellulose to solvent was varied, with greatest consequent transformation observed for c < 15%, where c is the weight of cellulose expressed as % of the total weight of cellulose, LiCl and DMAc. The dissolution time was varied between 1 h and 48 h, with only small additional changes achieved by extension beyond 4 h.

Keywords: All-cellulose composite; Cellulose I; Cellulose II; Cellulose IV; LiCl/DMAc; Microcrystalline cellulose; Solid-state 13 C NMR; X-ray diffraction

Domains: Chemical Sciences; Polymers; Chemical Sciences; Cristallography

Benoît J.C. Duchemin, Roger H Newman, Mark P Staiger. Phase transformations in microcrystalline cellulose due to partial dissolution. Cellulose, 2007, 14 (4), pp.311-320. ⟨10.1007/s10570-007-9121-4⟩. ⟨hal-02922530⟩