ALBERT

Notes: Viscosity, sedimentation, diffusion, and osmotic pressure measurements in ethyl acetate are reported on four unfractionated nitrocellulose polymers containing about 13.5% nitrogen and varying in molecular weight from 0.93 to 15 x 105.Detailed viscosity determinations in buret viscometers in the concentration range 0.025 to 0.300 g./dl. and over a range of velocity gradients from about 500 to 5000 sec.-1 are presented. Viscosity data adjusted to fixed shear rates fitted closely the relation ηsp/C = [η] + a2C + a3C2. Plots of ηsp/C vs. C at different shear rates were found to diverge rapidly with increasing concentration. For the nitrate of highest molecular weight, the viscosity was strongly shear-dependent and the intrinsic viscosity appeared to vary from 52 at 3000 sec.-1 to 80 or more at 0 sec.-1. The other samples displayed these tendencies less markedly with decreasing molecular weight. Other extrapolation procedures are also discussed. The intrinsic viscosity data accumulated at 500 sec.-1 could be represented by the relation [η] = KMα; α = 0.99; the molecular weights were those obtained from sedimentation-diffusion measurements on the unfractionated nitrocelluloses. Assuming for practical purposes α = 1, then Km (\documentclass{article}\pagestyle{empty}\begin{document}$\[= \overline {{\rm DP}} /[{\rm \eta ]}\]) is found to have the value 80 ± 3. Assuming a negligible depolymerization during nitration, the analogous factors required for cupriethylenediamine and for cuprammonium were found to be 170 and 230, respectively. The effect of varying shear rate on these factors is illustrated.The sedimentation constants obtained were readily extrapolated to infinite dilution with an expanded sedimentation-concentration relation, S = S0/(1 + K2C + K′s C2). Diffusion constants were obtained following the second moment method and mathematically extrapolated to zero concentration according to Gralén. Molecular weights were computed with the Svedberg equation. Number average molecular weights were obtained osmotically.Some consideration of the data in terms of the theories of Debye-Bueche and Kirkwood-Riseman is given. It is found that both K-R's and D-B's theories predict the variation of intrinsic viscosity with molecular weight within twice the standard deviation of the observed slope from the frictional coefficient-molecular weight data. In both viscosity and sedimentation the polymer appears, therefore, to behave in an approximately equally “free draining” fashion. For the calculated intrinsic viscosity of a sample of intermediate molecular weight a reasonable value is obtained from the latter theory only; but it is not uniformly successful in predicting all [η]'s, particularly those corresponding to low molecular weights.The relation between Ks, the first interaction coefficient in sedimentation and molecular dimensions, is briefly discussed. Also considered are the interaction coefficients in viscosity, especially as regards their dependence upon velocity gradient.

Notes: Five new diamine-cellulose complexes have been prepared from cotton by means of tri-, penta-, hexa-, hepta-, and octamethylenediamines. The diamine contents of the dry fibrous materials have been determined, and the characteristic x-ray diffractometer tracings have been obtained. Satisfactory x-ray fiber patterns could not be obtained for the hydrazine, hepta-, and octamethylenediamine complexes. The distention of the 101 interplanar spacing was found to be related linearly to the number of carbon atoms in the diamine molecule. Intensity of the diffraction also increased markedly with diamme chain length. Unit cell dimensions of the new complexes have been calculated. The x-ray data indicating that the 101 interplanar spacing is occupied by only one diamine molecule is supported by the analytical data showing a diamine content close to that required by an anhydroglucose-diamine ratio of 2:1.

Notes: The present paper reports the results of a study of the decomposition product of the ethylamine-cellulose complex obtained from cotton cellulose. It is shown that the cotton remaining after removal of ethylamine by distillation possesses a crystalline component identical with the ammonia-cellulose decomposition product designated by other workers as cellulose III. Certain important differences between ramie cellulose III and cotton cellulose III are discussed especially as regards the relative ease of recoversion to cellulose I. Experimental data are given showing the effect on degree of conversion of temperature, and of two different times of immersion in boiling water. Data are also given showing the effect on the structure of the decomposition product of time of immersion in ethylamine. An attempt is made to explain the appearance of a strong diatropic 020 interference in the x-ray patterns of the decomposition product and of the regenerated cotton cellulose I.

Notes: The ethylenediamine-cellulose complex, previously described by Trogus and Hess, has been reinvestigated with regard to its stability toward a series of solvents and to the differences in the fine structure of the cellulose remaining after its decomposition. It is shown that nonpolar solvents which do not contain oxygen have little effect on the complex; they do not reduce the diamine content or alter its crystal structure. On the other hand, it has been found that polar, oxygen-containing solvents almost completely remove the diamine and, in general, cause a reconversion of the crystal structure to the cellulose I crystalline modifications. The nature of the fine structure of the cellulose remaining after decomposition of the complex is discussed in relation to the directive or orienting influence of the solvent used for the decomposition. It is shown empirically that the directive influence of a solvent is related to its polarity and to the temperature at which the decomposition is effected.

Notes: The ethylenediamine-cellulose complex in the dry state has a sharp characteristic x-ray diffraction pattern and usually contains from 17 to 26% diamine when freshly prepared. High vacuum and elevated temperature failed to reduce this below 17%. Rapid decomposition of the complex as evidenced by the x-ray diffraction patterns was associated, however, with storage at room temperature in a paper envelope. A slow decrease in diamine content accompanied by shifts in the x-ray pattern resulted from storage under controlled conditions of temperature and humidity. An especially dried sample rapidly gained weight at first when exposed to the open air, then very slowly lost weight. There is an indication from the data that a 2:1 complex is present with two anhydroglucose units per diamine molecule, strongly suggesting a hydrogen-bonded crosslink. The increase in fiber cross-sectional area and the distention of the crystal unit cell are of an order of magnitude to suggest that complex formation can account for most of the fiber swelling.

Notes: Diethylenetriamine and cellulose form a stable complex with interplanar spacings of d101 = 11.54, d101- = 4.53, and d002 = 4.18 A. The spacings are almost identical to those of the ethylenediamine-cellulose complex. It is concluded from the x-ray data that the triamine molecule separates two cellulose chains and crosslinks them through the secondary and one primary amino group of the triamine.