title: Water Adsorption in Wood Microfibril-Hemicellulose System: Role of the Crystalline-Amorphous Interface.
abstract: A two-phase model of a wood microfibril consisting of crystalline cellulose and amorphous hemicellulose is investigated with molecular dynamics in full range of sorption to understand the molecular origin of swelling and weakening of wood. Water is adsorbed in hemicellulose, and an excess of sorption is found at the interface, while no sorption occurs within cellulose. Water molecules adsorbed on the interface push away polymer chains, forcing the two phases to separate and causing breaking of h-bonds, particularly pronounced on the interface. Existence of two different regions in moisture response is demonstrated. At low moisture content, water is uniformly adsorbed within hemicellulose, breaking a small amount of hydrogen bonds. Microfibril does not swell, and the porosity does not change. As moisture content increases, water is adsorbed preferentially at the interface, which leads to additional swelling and porosity increase at the interface. Young's and shear moduli decrease importantly due to breaking of h-bonds and screening of the long-range interactions.
authors: Chair of Building Physics, Swiss Federal University of Technology Zurich , Stefano-Franscini-Platz 5, 8093 Zürich, Switzerland.|Laboratory for Multiscale Studies in Building Physics, Empa, Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129, 8600 Dübendorf, Switzerland.
authors: Karol
authors: K
authors: Kulasinski
authors: Solid Earth Geophysics Group, Los Alamos National Laboratory , MS D446, Los Alamos, New Mexico 87545, United States.|Department of Physics, University of Nevada , 1664 North Virginia Street, Reno, Nevada 89557, United States.
authors: Robert
authors: R
authors: Guyer
authors: Laboratory for Multiscale Studies in Building Physics, Empa, Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129, 8600 Dübendorf, Switzerland.
authors: Dominique
authors: D
authors: Derome
authors: Chair of Building Physics, Swiss Federal University of Technology Zurich , Stefano-Franscini-Platz 5, 8093 Zürich, Switzerland.|Laboratory for Multiscale Studies in Building Physics, Empa, Swiss Federal Laboratories for Materials Science and Technology , Überlandstrasse 129, 8600 Dübendorf, Switzerland.
authors: Jan
authors: J
authors: Carmeliet
mesh_terms: D000327:Adsorption; D011134:Polysaccharides / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D011134:Polysaccharides; D014867:Water; C007916:hemicellulose