ISSN:0021-8995    

DOI:10.1002/app.1961.070051801

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1961

数据来源: WILEY

摘要:

AbstractXanthation can be accomplished by slurrying the alkali cellulose in an organic liquid chosen to be miscible with carbon disulfide, immiscible with water, and a nonsolvent for sodium hydroxide, alkali cellulose, cellulose xanthate, and other components of viscose. Straight‐chain hydrocarbons, such asn‐hexane and n‐heptane, satisfy these requirements and function very well. A viscose preparation system using this method of xanthation would consist of a slurry step wherein the alkali cellulose and carbon disulfide are reacted in the selected organic liquid, a filtering step to remove the xanthate from the liquid, and a mixing operation to dissolve the xanthate in weak alkali to produce viscose. Because of the near‐perfect distribution of carbon disulfide throughout the reaction, this method of xanthation produces filterable viscoses a t very low degree of substitution. It is also possible to produce viscose of identical composition at widely different process conditions by various combinations of temperature, reaction time, and carbon disulfide concen

ISSN:0021-8995    

DOI:10.1002/app.1961.070051802

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1961

数据来源: WILEY

摘要:

AbstractThe coagulating and regenerating conditions that are necessary for the formation of a highly durable cellulosic film are described. It is shown that low orientation, low lateral order, low gel swelling, and cellulose with a highDPare primary requisites for best film properties. Experiments demonstrated that the application of a unidirectional stress produced an unbalance of physical properties in the film, and this, in general, had an adverse effect on the durability level of a packaging film. Studies of the rates of loss of water and sodium hydroxide from the viscose during coagulation revealed that thermal and osmotic effects were not as important in determining the rate of coagulation as was the buffering and neutralizing capacity of the bath. A bath with high acid content caused the cellulose to be regenerated prior to collapse of the sheet.

ISSN:0021-8995    

DOI:10.1002/app.1961.070051803

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1961

数据来源: WILEY

摘要:

AbstractRegenerated cellulose film prepared by a dry‐cast method has demonstrated outstanding superiority over similar film produced by the conventional wet‐cast process. Factors contributing to the superior quality of film prepared by the dry cast process are: (1) physical properties several times greater than for wet‐cast film of corresponding thickness; (2) high durability at conditions of low temperature and low humidity even without the addition of softening agents, and (3) outstanding dimensional stability when exposed to conditions of varying temperature and humidity. The dry‐cast cellophane differs structurally from the commercial product in having a lower degree of order, a lower degree of swelling in the gel form, and minor differences in molecular orientation. A commercial process for producing dry cast cellophane may be envisioned as a heated, polished support for drying the viscose film; a regenerating system of alcoholic hydrochloric acid, hot glycerine, or a hot, oxygenfree gas; a water both for purifying the film; and a conventional cellophane dryer. The ideal viscose composition for producing dry‐cast cellophane is high cellulose content, moderately highDP, sufficient degree of substitution on the cellulose to yield a high degree of dispersion, and low causti

ISSN:0021-8995    

DOI:10.1002/app.1961.070051804

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1961

数据来源: WILEY

摘要:

AbstractLight‐scattering and viscosity measurements were obtained for seven fractions of the diethylacetamide derivative of cellulose xanthate (DAX) in 90% dimethyl sulfoxide. The degree of substitution (D.S.) range represented by the samples was 0.4 to 1.22; the molecular weight range was 112,000 to 446,000. The following empirical equation between the intrinsic viscosity and D.P.wwas found: [η] = (5.63 – 3.35 D.S.) × 10−3D.P.w. As reflected by thekm– D.S. plot, the Martin constants, and the configuration parameters, it was apparent that the low D.S. derivatives are considerably more extended in solution than high D.S. derivatives of the same chain length. Under such conditions, it is apparent that solvent‐polymer interaction has assumed an important role in determining the polymer configuration. The behavior of the DAX molecule in solution was found to be strikingly similar to that of other cellulose derivatives. Hydrodynamic considerations revealed that the behavior in solution appears to approach that of the more flexible synthetic polymers at D.S. levels above 0.9 and molecular weights ab

ISSN:0021-8995    

DOI:10.1002/app.1961.070051805

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1961

数据来源: WILEY

摘要:

AbstractThe viscoelastic properties of regenerated cellulose containing several different softeners or water only were investigated. Measurements of creep and Young's modulus were made on the Instron tensile tester, and the creep curves were fitted to a mechanical model consisting of Voigt and Maxwell elements of springs and dashpots in series. The elastic and viscous parameters were determined for the various softened films and compared with each other and with measurements of Young's modulus. It was found that the elastic modulus is a function of the effective molar concentration of the softener in the film which is related to its ability to break hydrogen bonds. The inelastic deformation was found to be a linear function of the heat of vaporization of softener (including water) in the film which is related to hydrogen‐bonding energy. Thus, inelastic deformation requires breaking of interchain hydrogen bonds in contrast to pure elastic deformation which involves stretching of hydrogen bonds. A relationship of the Voigt unit and of the Maxwell unit on the composition of the cellulose‐softener system and on cellulose‐softener interaction has been demonst

ISSN:0021-8995    

DOI:10.1002/app.1961.070051806

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1961

数据来源: WILEY

摘要:

AbstractThe dynamic elastic modulus of cellophanes has been measured by use of the resonant frequency of a 2 × 60‐mm. strip of film in longitudinal vibration. The niodulus was computed from the resonant frequency length of specinieii, and the cross‐sectional area determined from its resonant frequency in transverse vibration. The apparatus is described briefly. Unsoftened film and glycerol‐softened films containing 7.3, 13.7, and 21.3% glycerol prepared from the same roll of never‐dried regenerated cellulose were conditioned a t 75°F. and 15, 35, and 81% R. H., and the elastic moduli were measured in both directions. Moisture and softerier contents were determined. The reciprocals of the geometric means of the moduli in the machine and transverse directions were plotted as a function of the volume of film containing 1 g. of cellulose. The displacement of the curve obtained for each softened film from the curve for the unsoftened film measures the effect of the softener, since the curves would coincide if the effect of softener were from swelling only. This permits construction of an empirical equation for the modulus of these glycerol‐softened films as a function of moisture and softener content. It was found further that the logarithms of the corrected compliance (1/EV2/2c), whereEis the geometric mean modulus andVcis the volunie of film containing 1 g. of cellulose, gave a straight line when plotted as a function of the number of moles of water plus twice the number of glycerol present in 100 g. of cellulose. This indicates that the effect of a mole of glycerol in breaking up the hydrogen‐bonded structure of the cellulose is twice as great as that of a mole of water. These results have been compared with similar results obtained on films containing ethylene carbonate and ethylenediamine. With the exception of ethylenediamine‐treated films studied a t high humidities, these fdms gave points falling approvimately on the corrected compliance curve obtained for the glycerol‐softened and unsoftened films. For these films, however, the simple sums of moles of water plus moles of ethylene carbonate or ethylenediamine monohydrate present in 100 g. of cellulose were used rather than the weighted sum used for the glyce

ISSN:0021-8995    

DOI:10.1002/app.1961.070051807

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1961

数据来源: WILEY

摘要:

AbstractRayon monofilaments containing 80% activated carbon were prepared. They are an effective medium for adsorbing noxious odors. High grade gas‐adsorbing carbons are intimately bound in a cellulose matrix by niising the carbon in viscose ‘sodium cellulose xanthate solution’ and extruding the mixture through a special conjugate jet as iiioiiofilaments into a rayon coagulating bath. The special jet permits a backbone of plain viscose to be spun as a spine support for the carbon‐loaded portion of the monofilament to give it added strength. The diameters of the dry, nondusting monofils can be varied greatly. For air cleaning purposes the nonfilanients range from 1/64 to 3/64 in. in diameter. Although imbedded in cellulose, the carbon's capxity to remove malodors remains high. In addition, when made into a filter unit, the resistance to air flow through the unit is low. The novel use of regenerated cellulose as a carrier for large quantities of activated carbon indicatcs that other materials (catalysts, ion exchange resins, etc.) can be similarly bound in cellulose and still retain a high level of their original perf

ISSN:0021-8995    

DOI:10.1002/app.1961.070051808

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1961

数据来源: WILEY

摘要:

AbstractThe odor control performance of carbon‐loaded rayon monofilaments depends on the type and proportion of activated carbon used. The filter efficiency in turn determines the rate of odor reduction in a closed space and the ultimate or equilibrium concentration when odorant generation and removal occur simultaneously. Four types of filters were evaluated: rayon loaded with air‐ or water‐purification carbon, granular air‐purification carbon, and open‐lattice commercial filters. Air laden with synthetic tobacco malodor was streamed through successive increments of adsorbent bed. Sensory odor judgments were made before and after each adsorption stage by matching the effluent odors with those from mixtures of known concentrations. It was thus possible to estimate adsorption efficiencies and, by repeating the measurements after various degrees of carbon saturation, to construct adsorption waves. It was found that airpurification carbon was superior to water‐purification carbon for loading in the rayon filaments, and that all the rayon‐carbon compositions were much superior to the commercial open‐lattice filters. The rayon‐carbon filters showed efficiencies up to 70% for one pass at 0.1 sec. detention time through a 3/4‐in. bed packed at 0.096 g./ml. with a filament comprising 20% r

ISSN:0021-8995    

DOI:10.1002/app.1961.070051809

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1961

数据来源: WILEY

摘要:

AbstractCellulose was regenerated from technical viscose as bulk gels and thin films (never dried) and then conditioned by repeated swelling with sodium hydroxide solutions and steam treatments. These extraction and conditioning treatments of the gels increased the crystallinity and decreased the accessibility to water as measured by x‐ray, infrared, and density measurements. The density of the gels increased more during these treatments than one would expect from the increase in crystallinity as measured from x‐ray diffraction. Supported by the combined density, infrared, and D2O‐exchange data, this was taken as evidence that the conditioning also gives a closer packing or an increased order in the so‐called amorphous regions. Both steam‐conditioning and drying decreased the accessibility of thin films as measured by a combination of infrared analysis and swelling with sodium deuteroxide solutions in heavy water (NaOD in D2O). Reports in the literature that regenerated cellulose is completely accessible in dilute aqueous alkali solutions (about 1%) have not been verified. The intensity ratios of the different infrared absorption bands were measured during the gradual swelling and exchange with NaOD of increasing concentrations from 1 to 16% in D2O. The few data available now seem to indicate that hydroxyl groups assigned to intrachain hydrogen bonds in crystalline regions are more resistant to deuterium exchange than hydroxyl groups assigned to interchain hydrogen bonds. Based on these studies the concepts of crystallinity, order, and accessibility to water and swelling agents for regenerated cellulose are

ISSN:0021-8995    

DOI:10.1002/app.1961.070051810

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1961

数据来源: WILEY