Fine Structure Of Cellulose Research Articles

Derivative Infrared Spectra of Ramie

A derivative technique has been applied to infrared absorption spectrophotometry of ramie in the regions 4000-2500 and 2000-700 cm-1. The second derivative spectra at different scan speeds and differentiator time constants in these regions have been compared with the absorption (zeroth derivative) spectra. The derivative spectra mea sure the slope or curvature of the absorption contours, facilitate to resolve, and detect absorptions that are unresolvable due either to band overlap or low intensity. This method may thus provide more detailed information on the fine structure of cellulose.

Modification of the fine structure of cellulose by halogen and heat treatments

AbstractTreatment of various celluloses such as cotton, sulphite, and sulphate pulp with bromine water brings about profound changes in the fine structure of the fiber. Depending on the conditions of the treatment and on the nature of the cellulose, increases or decreases in the accessibility of the cellulose are observed, indicating crystallization and decrystallization processes. In the case of bleached sulphate pulp, similarly to rayon previously studied, an initial decrystallization proceeds the crystallization step. These changes were determined by the IR method, which was correlated previously to the bromine accessibility method. They are accompanied by highly significant changes in moisture absorption. The crystallization proceeds according to first‐order kinetics with respect to the concentration of the less‐ordered regions (LOR) of the cellulose. The rates of crystallization for the various celluloses varied in a range of 4 orders of magnitude. The activation energies of the bromide induced crystallization were found for all celluloses to be in the range of 10–15 kcal/mol, as compared to 30–40 kcal/mol obtained upon crystallizing the same celluloses by heating in the temperature range of 180–200°C. These values correspond to those of solvent and thermal crystallizations of poly(ethylene terephthalate), indicating the similarity between the crystallization mechanisms of the two polymers.

Kinetics of simultaneous decrystallization and crystallization induced in high‐modulus rayon by bromine water

AbstractStudies of the effect of aqueous Br2 solution on the fine structure of cellulose have shown that the accessibility of the cellulose is a complex function of the duration of treatment. Following immersion of rayon‐cellulose in the Br2 solution, its accessibility is observed to increase until a peak is reached, after which the accessibility decreases with time. For higher temperatures and greater concentrations of Br2, a sharper peak and faster rates of increase and decrease of accessibility are obtained. In order to explain this behavior, a mathematical model of the kinetics is postulated involving two opposing first‐order processes occurring simultaneously. One process describes the decrystallization of crystalline regions within the cellulose by opening intermediate linkages due to Van‐der‐Waals forces involved. The second process relates to the crystallization of the less‐ordered regions. The rate constants for these processes are determined by fitting experimental curves to the postulated analytical expression with the aid of a digital computer program. Experiments carried out on high‐modulus rayon showed that for this type of cellulose, the effect described above was very pronounced. From the calculated rate constants, the activation energies of the crystallization and decrystallization reactions were determined. The plots of the rate constants versus 1/T showed that a break occurs at 25°C, corresponding to a second‐order transition point of cellulose. The energies of activation of the crystallization process are in the range of 7–9 and 10–13 kcal/mol in the temperature ranges 10–25 and 25–40°C, respectively. The activation energies of the decrystallization process are 13 and 18–24 kcal/mol in these temperature ranges.

FINE STRUCTURE OF TOBACCO CELLULOSE

Fine structure of tobacco cellulose was studied with respect to the change of highly ordered region of cellulose by the alkali treatments.Holocelluloses were prepared from leaf midribs and stalk shreds of native and flue cured tobaccos by the peracetic acid method. The leaf midrib holocellulose has a larger quantity of mannose and smaller quantity of xylose than the stalk holocellulose. It should be emphasized that the hemicellulose of leaf midribs is softwoodlike, while the hemicellulose of stalk is harwood-like. There is no characteristic difference in sugar composition between native and flue cured tobaccos.A conclusion that the highly ordered region of stalk cellulose is larger in size and higher in degree of order than that of the leaf midrib cellulose can be drawn from the lateral order distribution of cellulose and acid hydrolysis rate constants, water adsorption and average degree of polymerization of hydrolyzed residue of alkli treated holocellulose.The amounts of crystalline region and the levelling-off DP of flue cured tobacco cellulose: are larger than those of native tobacco. However, there is no remarkable difference in the fine structures of cellulose between native and flue cured tobaccos.Comparing with wood cellulose, tobacco cellulose has a larger solubility in alkali fractional dissolution. The levelling-off DP of alkali treated tobacco cellulose is about one half of that of wood cellulose. The water adsorption of the highly ordered region of the alkali treated tobacco cellulose is higher than that of wood cellulose by 1%.These results show that the highly ordered region of tobacco cellulose is smaller in size and lower in degree of order than that of wood cellulose.

Electron paramagnetic resonance spectroscopy of γ‐irradiated cellulose and related compounds

AbstractEPR studies were carried out on different irradiated cellulosic materials. The shape of the EPR spectrum was found to depend upon the fine structure of cellulose. The peak‐to‐peak distances of the large peaks on the differential curves were found to be 23.3 and 24.8 gauss, respectively, for the amorphous and recrystallized cellulose. The number of free radicals present per unit weight in the recrystallized cellulose and in the amorphous cellulose were found to be in the ratio of 2.1:1. The EPR spectrum of a sample of irradiated cotton crystallites which was soaked in acetone before being dried was markedly symmetrical, in contrast to the EPR spectra of samples of cotton linters and of cotton crystallites dried from water, and was considered to be a reflection of the lower intermolecular bonding in the former. For corresponding doses, the free radicals on cotton crystallites have the highest g value, followed by cotton linters, followed by regenerated cellulose I. The g value decreased as the irradiation dose was increased.

Physical and fine structure properties of cotton fibers swollen with trimethylbenzylammonium hydroxide

AbstractCotton fiber was treated with aqueous trimethylbenzylammonium hydroxide (Triton B) at concentrations over the range 25%–40%. After complete removal of the swelling agent, the samples were evaluated for the extent of swelling, strength and elongation, birefringence, moisture regain, density, crystallinity, x‐ray diffraction patterns, and microfibrillar morphology. Electron‐microscopical examination and other evaluation of fine structure properties revealed that the nature of swelling is intercrystalline up to 30% concentration of Triton B, and intracrystalline beyond that. Although the swelling as measured by propanol‐2 retention after treatment with 30% Triton B is about twice as much as that of the control, the original structure remains almost unchanged except for some gain in strength and elongation and increase in moisture regain. At 32% Triton B concentration and beyond, rapid decrystallization takes place, accompanied by a fall in birefringence, density, and crystallinity index. X‐Ray analysis showed significant loss of lateral order and partial conversion of cellulose I to cellulose II at 35% and 40% Triton B concentrations. The results indicate that, used at the critical concentration of 30%, Triton B can be a useful swelling agent for cotton fibers as it opens up the fine structure of cellulose considerably without impairing any important physical properties.

Effect of chemical reagents on the fine structure of cellulose. Part IV. Action of caustic soda on the fine structure of cotton and ramie

AbstractAn x‐ray study has been made of the changes in lateral order that take place on the treatment of cotton and ramie with different concentrations of caustic soda at 0 and 20°C. When mercerization conditions are reached it is found that there is an increase in lateral disorder in the fibrils. The x‐ray diagrams from samples treated in the higher concentrations of caustic soda reveal a residual diffraction effect that can be interpreted in terms of a special type of cellulose sheet. This result implies one extreme of lateral disorder that is present in the fine structure of these materials. Indication is given how these lateral disorder phenomena can affect reactivity.

Effect of chemical reagents on the fine structure of cellulose. Part III. Action of caustic soda on cotton and ramie

AbstractThe changes in x‐ray orientation brought about by the treatment of cotton and ramie with caustic soda of different concentrations have been studied. With ramie the effect of the treatment is to decrease the x‐ray orientation, while with cotton the reverse is true. The cause of this difference is traced to a difference in the morphology of the two fibers rather than a difference in their fine structure.

Effect of chemical agents on the fine structure of cellulose. Part II. The action of acetyl chloride

The action of acetyl chloride on the fine structure of regenerated cellulose (fiber and film) has been studied by infrared and x-ray techniques. The two techniques reveal different aspects of the fine structure and are therefore complementary. The changes found on acetylation appear to show that the molecular network theory is inadequate to describe the fine structure of the samples of regenerated cellulose studied. The observed effects can be explained more satisfactorily in terms of a structure in which highly oriented crystallites are interspersed with regions that are highly oriented but not as well ordered, resulting in a variation in density across the cross section.

Effect of chemical reagents on the fine structure of cellulose. Part I. Action of diazomethane

AbstractAn infrared and x‐ray study of the action of diazomethane on the fine structure of ramie and regenerated cellulose (fiber and film) has been made. It has been found that the methylation process affects the disordered regions, and also parts of the structure that are sufficiently highly ordered to be detected by x‐ray methods but whose hydrogenbond order is too low to be detected by the infrared‐deuteration technique. The effect of partial methylation on the hydrogen bonding in the noncrystalline regions is described and discussed. The conclusion drawn from the results is that diazomethane can react in the noncrystalline and the imperfectly crystalline regions, but not in the highly ordered crystalline regions.

Studies in the Reaction of Formaldehyde with Unmodified, Modified, and Dyed Celluloses: Part III: The Reaction of Formaldehyde with Oxycelluloses

The reaction of formaldehyde with oxycelluloses obtained by the oxidation of cotton cellulose with four oxidizing agents is investigated. The rate and the extent of the reaction with these oxycelluloses before and after their treatment with chlorous acid and sodium borohydride have been studied to see the effect of oxidative modification of cellulose on its reaction with formaldehyde. It is observed that the rate and extent of reaction depend upon the nature and extent of oxidation, the change in the fine structure of cellulose during oxidation, the subsequent treatments, and the carboxyl content. A tentative mechanism for the inhibiting action of carboxyl groups present in the anhydroglucose units of the cellulosic material has been suggested.

X線分析によるセルロースの微細構造,ことに結晶化に関する研究

X線分析によるセルロースの微細構造,ことに結晶化に関する研究

Fine Structure of Cellulose and other Microfibrillar Substances

Fine Structure of Cellulose and other Microfibrillar Substances

(11)繊維素微細構造の化学的観察法についての考察

(11)繊維素微細構造の化学的観察法についての考察

Causes of Unlevel Dyeing of Cotton Cellulose

Journal of the Society of Dyers and ColouristsVolume 67, Issue 10 p. 357-361 Causes of Unlevel Dyeing of Cotton Cellulose The Influence of Mercerising and Bleaching Processes on the Fine Structure of Cellulose I. Gailey, I. GaileySearch for more papers by this author I. Gailey, I. GaileySearch for more papers by this author First published: October 1951 https://doi.org/10.1111/j.1478-4408.1951.tb02673.xCitations: 8AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume67, Issue10October 1951Pages 357-361 RelatedInformation

Crystallinity of Cellulose and Its Significance for the Fiber Properties

The subject of this paper is treated mainly from the standpoint of cotton cellulose. The concept of crystallinity is discussed not simply in the narrow sense of degree of crystallinity but in the broader sense, which involves the whole fine structure of cellulose. With respect to crystallinity in the latter sense, there are four main factors, each involving a mean value and a distribution of values, both mathematical and spatial. These parameters, independent within certain limits, are (1) the nature of the crystal lattice, (2) the percentage of crystalline ma terial, (3) the size of the crystallites, and (4) the orientation of the crystallites. A well- planned analysis of covariance between these factors and the important physical properties of cotton would be desirable. This would be a task of considerable magnitude even if other variables not directly related to crystallinity, such as molecular size and morphology, were not active. In the absence of such an analysis it is still possible to show the marked influence of some of these parameters on certain of the important physical properties of cotton. The relation of physical properties to the crystalline modification has been pointed out frequently by a com parison of the properties of the native fibers with those of regenerated fibers or with those of mercerized fibers. However, the changes in the percentage of crystalline material which usually occur in these transformations have not been evaluated exactly, and the conclusions drawn from previous studies should probably be checked. Decreased crystallinity and higher content of amorphous cellulose is symbatic with in creased elongation, increased moisture regain, and increased chemical reactivity. Of particular interest in the last category is the special case of hydrolysis, a reaction in which it is possible that crystallization may occur. Data on the third parameter, the size of the crystallite, are too scanty to permit any con clusions to be drawn. A study of this factor will have to wait on improved methods for meas uring the size and size-distribution of the crystalline areas. The increase of fiber strength and of refractive index with improved orientation has been well established. A decrease in elongation usually accompanies this.

X-ray Analysis of Textile Fibres

A concept concerning the secondary structure of cellulose, paralleling that proposed by Zwicky for inorganic orystals, is suggested in the hope that the present conflicting theories regarding the fine structure of cellulose may be harmonized. This picture may be described as a compromise between the concept of discrete micelles or well-defined crystallites on the one hand, and the existence of a continuous structure on the other. There appears to be nothing in the X-ray data to belie the concept of secondary structure for cellulose.