Relation of certain infrared bands to cellulose crystallinity and crystal latticed type. Part I. Spectra of lattice types I, II, III and of amorphous cellulose

Abstract

The infrared spectra of highly crystalline samples of cellulose containing the lattice types I, II, and III were compared with one another and with the spectrum of amorphous cellulose in the 850–1500 cm.−1 region. The spectra of cellulose II and of amorphous cellulose showed interesting similarities at 1420, 893–897, and 1111 cm.−1, three bands which others have used to follow changes in crystallinity and lattice type because the spectrum of cellulose I differs distinctly at these points from that of amorphous cellulose or cellulose II. The similarity between amorphous cellulose and cellulose II prevents the use of these bands for crystallinity determination in samples with mixed lattice types–for instance, partly mercerized cotton. An explanation is offered for the resemblance of the two spectra, based on the hypothesis that a rearrangement of intramolecular hydrogen bonds, tending to stabilize a different conformation of the cellulose chain, occurs upon destruction of the native cellulose I crystal lattice.