The Effect of Variations in Degree of Structural Order on Some Physical Properties of Cellulose and Cellulose Acetate Yarns

Abstract

It is shown by means of x-ray diffraction diagrams that cotton, a highly crystalline and oriented material, gives a triacetate of low crystallinity which may be rendered more crys talline by annealing. This triacetate is partially hydrolyzed to form the secondary cellulose acetate used in textile yarns, which gives an x-ray pattern showing a highly amorphous structure. Although steric effects prevent increases in crystallinity by annealing, this type of yarn can be oriented, the degree of orientation depending upon the conditions under which stretching of the yarn takes place. By swelling and allowing limited mobility, this orienta tion may be increased over that produced by dry stretching. Cellulose acetate fibers may be converted into highly crystalline celluloses, the orientation of the original material carrying over into a hydrolyzed product. The load-elongation characteristics of families of these 2 types of yarns are described and the effects of orientation are discussed. The decrease in lateral strength, due to orientation, is illustrated by means of electron micrographs of the material. The relationship between orientation in series of cellulose acetate and correspond ing cellulose yarns having greater or lesser degrees of orientation and the sonic moduli of these materials are illustrated. Possible explanations are suggested. Dye retention simi larities between mature cotton and slightly oriented cellulose yarn on one hand and immature cotton and unoriented cellulose yarn on the other hand are given to indicate that orientation may be one basic difference between mature and immature cottons.