ABSTRACT

Cellulose chains take various shapes besides the usual form which is a ribbon with a 2-fold screw axis. Examples of other shapes include cellulose nitrate and soda cellulose II. In amorphous regions and in solutions, cellulose molecules adopt irregular shapes, with short segments that can be described approximately by screw-axis descriptors. Although fiber crystallography is important in determining basic molecular shape, worthwhile information also comes from energy calculations. In particular, energy calculations are important for determining the feasibility of unusual proposed structures and for defining the expected ranges of molecular shape in amorphous regions. Two unusual shapes investigated in the present work were a helical complex with iodine and a fold.