A study of the kinetics of the heterogeneous hydrolysis of cellulose indicates that there are two distinct rates which have been attributed to the rapid hydrolysis of the loose amorphous regions and to the slow hydrolysis of the dense crystalline portions of the fiber. Based on this interpretation, a simple method for the determination of the relative proportions of crystalline and amorphous cellulose has been developed. The method was applied to a series of natural and regenerated cellulose fibers and the resulting "degree of crystallinity," defined as the amount of crystalline cellulose in a sample expressed as a decimal fraction of the total cellulose, was tabulated. Results obtained on four samples of rayon are very well correlated with crystal linity data derived from x-ray diffraction patterns. There is apparently no correlation between the degree of crystallinity and the tenacity of five samples of rayon. In six samples of Stone , ville cotton there appeared to be no relationship between the degree of crystallinity and crystal lite orientation. There are indications that the ultimate elongation and the moisture absorption of the rayon samples are proportional to the content of amorphous cellulose.

In a continuation of a previously reported investigation into the effect of the catalyst in the cotton cellulose–DMEU reaction, experiments were performed in which the four inorganic salt catalysts originally studied, MgCl2, Mg(NO3)2, ZnCl2, and Zn(NO3)2, were employed at the higher metal ion concentration of 0.1M, and CuCl2 and CdCl2 were employed at 0.03M concentration. Data from infrared absorption spectra of the treated cotton products were in agreement with those obtained at the 0.03M catalyst concentration, again indicating that the catalyst entered into the reaction, forming a coordination complex through the formation of nitrogen‐to‐metal bonds between the catalyst and the DMEU molecule. Similarly, it was again indicated that reaction with DMEU takes place preferentially at the primary alcohol group of the anhydroglucose unit. Analyses of IR data indicated a higher degree of crosslinking, and thus fewer terminal OH or NH groups at the 0.03M catalyst than at the 0.1M catalyst concentration. Further evidence of complex formation was obtained from infrared spectra of the product of the CdCl2–DMEU reaction carried out in the absence of cellulose. Supplemental physical data obtained on products of reactions catalyzed with CdCl2 and CuCl2 at the 0.03M level, when compared with those obtained on products catalyzed with MgCl2 and ZnCl2, supported the earlier hypothesis that chlorine damage during heating was dependent upon the ability of the metallic complex to act as a free‐radical trap. Additional support for the free‐radical mechanism was obtained when treated cloth subjected to chlorination and exposed to ultraviolet radiation suffered the same discoloring and degradative effect as cloth chlorinated and subsequently scorched according to the usual AATCC method. Reaction rates of the cellulose–DMEU reaction at 45, 55, and 65°C. with each of the four catalysts at the 0.03M concentration were determined by following changes both in nitrogen and formaldehyde content as well as in crease recovery properties. The reaction was found to be pseudo first order when followed to 2/3 completion, and the catalysts, when ranked according to greatest to least effect upon the reaction rates, followed the order: Zn(NO3)2 > ZnCl2 > MgCl2 = Mg(NO3)2. Enthalpies, entropies, and free energies of activation have confirmed the earlier hypothesis that the metal ion enters into the reaction, forming a transition state complex.

In an effort to develop a simple and rapid means of measuring swelling capacities in water of cotton and other fibers in mass, the centrifuge technique has been subjected to a rather extensive study. In this technique the swelling capacity appears as a function of the moisture retention after swelling and centrifuging.Many previous workers have employed the centrifuge empirically for the removal of external, nonswelling water from fibers, but under conditions which have varied greatly as to time and intensity of centrifuging. In the present work, the complication of dealing with the two variables of time and speed of centrifuging simultaneously has been circumvented by noting that straight lines (to a high degree of approximation) were obtained when the moisture regains of the sample were plotted against the squares of the rotational speeds. The intercept of these straight lines on the moisture regain axis was characteristic for a given fiber in a given physical form. The intercept values were shown to be the same and reproducible for any selected centrifuging time of 20 min. or more, provided the minimum acceleration was above 3,200 g.It was found that the zero-speed intercepts on the moisture regain axis, while highly reproducible, did not represent true swelling capacities. That the intercept values were too large was shown by the sizable intercepts obtained with glass fibers, which obviously are incapable of swelling.It was found that the excess moisture retentions could be reduced considerably in samples "oriented" so that the axis of the yarns or cords lay parallel to the direction of centrifugal force. Still further reductions occurred on cutting such "oriented" samples after centrifuging and determining the moisture regains of the cut lengths nearest the centrifuge axis.

Cotton print cloth has been treated with 0.55 M aqueous solutions of 1,3-dimethyl- 4,5-dihydroxy-2-imidazolidinone or dimethylhydroxyethyleneurea (DMeDHEU) in the presence of either ZnCl2, Zn(NO3) 2, MgCl2, or Mg(NO3)2 catalyst at 0.03 and 0.1 M concentration of metal ion. The rates of the reaction at 45, 55, and 65°C in the presence of each of the above catalysts at 0.03 M concentration of metal ion have been determined by following the changes in bound nitrogen. Changes in wet and conditioned crease recovery with reaction time were also followed. Enthalpies, entropies, and free energies of activation at 45°C have been calculated. The kinetics followed a pseudo first-order reaction with zinc salts and zero-order reaction with magnesium salts. With zinc salt catalysis, substitution of the amido hydrogens by methyl groups in DMeDHEU increased the reactivity of the ring hydroxyl groups when comparison was made with dihydroxyethyleneurea (DHEU) and dimethyloldihydroxyethyleneurea (DMDHEU).