title: Determination of cellulose crystallinity from powder diffraction diagrams.
abstract: One-dimensional (1D) (spherically averaged) powder diffraction diagrams are commonly used to determine the degree of cellulose crystallinity in biomass samples. Here, it is shown using molecular modeling how disorder in cellulose fibrils can lead to considerable uncertainty in conclusions drawn concerning crystallinity based on 1D powder diffraction data alone. For example, cellulose microfibrils that contain both crystalline and noncrystalline segments can lead to powder diffraction diagrams lacking identifiable peaks, while microfibrils without any crystalline segments can lead to such peaks. This leads to false positives, that is, assigning disordered cellulose as crystalline, and false negatives, that is, categorizing fibrils with crystalline segments as amorphous. The reliable determination of the fraction of crystallinity in any given biomass sample will require a more sophisticated approach combining detailed experiment and simulation.
authors.affiliation: Biosciences Division, UT/ORNL Center for Molecular Biophysics, Oak Ridge National Laboratory, 1 Bethel Valley Road, Bldg. 6011, Oak Ridge, TN 37830-6309.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Lindner
authors.forename: Loukas
authors.initials: L
authors.lastname: Petridis
authors.forename: Paul
authors.initials: P
authors.lastname: Langan
authors.forename: Jeremy C
authors.initials: JC
authors.lastname: Smith
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D018360:Crystallography, X-Ray; D033362:Powder Diffraction; D014961:X-Ray Diffraction
chemical_list: D002482:Cellulose
keywords: X-ray scattering; finite crystallites; molecular modeling; noncrystallinity