Joseph J. Creely

Part II: Effects of Strains During Swelling, Washing, and Drying

Yarns from samples of Pima S-1 and Hopi Acala varieties were merceriud and decrystallized when strain was controlled to provide unrestricted shrinkage in length, normal length, and 3% extension beyond normal length during ethylamine treatment. Comparisons of effects of sodium hydroxide and ethylamine at different strain conditions were made from measurements on the cellulose, tensile properties of fiber bundles and yarns, and elastic behavior of the yarns. Densities of the mercerized are in general below those of the decrystallized if occluded solvents are removed. The lower densities are in accord with the higher moisture regains for mercerized than decrystallized cottons. Strains had no influence on the crystallinity ratio during decrystallization but pre vented complete conversion to cellulose type II in mercerization. The decreases in bundle tenacities with increases in gauge length were essentially equal in the decrys tallized and untreated cottons but smaller in the mercerized. Yarn tenacities of the mercerized and untreated increased as the moisture regain was increased, white those of the decrystallized were essentially equal at standard and wet conditions. Elongation at break was decreased by strain during treatment and increased with moisture in the sample when tested. The slack mercerized or decrystallized yarns when strained to less than 2% of their elongation at break have greater recovery and less permanent set than the untreated. At high strains or stresses the reverse in recovery and permanent set was found. Yarns treated at normal length have no appreciable difference in re covery and permanent set from that of the untreated.

The Effect of Humidity on the Crystallinity of Cellulose

in the 100% cotton, except that damage is less severe or extensive in the blend. A typical specimen from cotton shirts worn and launciered . 2~ times (Fin 5a) shows the messy arrangement of the fibers; many have been plucked out of their respective yarns and l~e tangled on the fabric surface. Some fibers are missing altogether from certain areas of the yarn structure leaving small holes. Many fiber ends are visible; in this case, many more are broken off and worn smooth ( Fi~;. 5b) than in the case of samples from shirts which had been laundered-only. Here, too, diagonal cracks were seen, with shredding and sheaves of fibrils on some of the fiber ends.

The Transformation of Acetylated Cotton Cellulose From Triacetate I to Triacetate II with Retention of the Fibrous Form

. Sprague and co-w orkers [ ? ) studied the etfect of various organic media on the crystal structure of cellulose triacetates I. and I I. They state that if the triacetate I. foriiie(I hy heterogeneous acetylation of the cellulose with retention of fibrous form, is dissolved in an organic solvent and then precipitated out. the product is always in the triacetate II form. However, they were unahle to obtain transformation of the triacetate ! I to triacetate lI I hv swelling. without loss of nbrous form. They also concluded that upon saponincation. triacetate I is always converted to the native or cellulose I furiii. while triacetate II is always converted to the cellulose II form.

X-Ray Diffractometer Thermal Technique for Study of Structural Changes in Cellulosic Compounds1

Previous x-ray diffraction studies of cellulose derivatives and other organic com pounds have shown that heat often has important effects, facilitating crystallization, transitions, and polymorphic transformations. However, the application of heat treat ments in conjunction with x-ray diffraction studies has usually been laborious, inexact, and at times ambiguous because of limitations of the technique. The present paper describes the adaptation of an x-ray furnace in conjunction with a two-pen potentiometer recorder and temperature-program controller to overcome some of the previous limita tions. A specially designed specimen holder is described. Thermal diffractograms of cellulose acetate and of benzyl and cyanoethyl cellulose are reproduced to demonstrate some of the advantages and possibilities of this technique.

Deswelling of Swollen Cotton Yarns as Measured by Propanol-2 Retention:

The assumption that one can swell cotton and then exchange the swelling agent with another solvent without significantly affecting the swollen sample is the basis of a recent method developed by Andrews and Oberg [1] for the measurement of degree of swelling of cotton and wood cellulose. This method offered a chance to test some ambiguous results that we had obtained in working with quaternary ammonium hydroxides as swelling agents. Previous work indicated that exchanging from aqueous benzyltrimethylammonium hydroxide (BTMOH) to 95% ethanol re-

Concerning Terminology for Empirical Measurements of Crystallinity: Southern Regional Research Laboratory New Orleans 19, Louisiana January 14, 1960

. same term and its abbreviation in two of his papers [ 1, 2 ) , one of which we give as a reference in our own paper. He feels that our use of the term and symbol will lead to confusion and proposes that we should &dquo;hit upon a new name&dquo; for our relationship. He would apparently limit the term &dquo;Crystallinity Index&dquo; to his &dquo;empirical dimensionless figure which represents the state of crystallinity of cellulose as a whole&dquo; and which is taken from the height and the base width of the principal (002 in cellulose I : 101 + 002 in cellulose I I ) densitometer peak of a photographic recording of the x-ray pattern of cellulose. While we regret our unintentional use of the same term and symbol, as used by Dr. Ant-Wuorinen, for our somewhat different set of diffractometer