Native Cotton Research Articles

Crystallinity of Native Cotton—Does it Influence Other Fiber Properties?

Crystallinity of Native Cotton—Does it Influence Other Fiber Properties?

Crystallinity, Crystallite Size, and Physical Properties of Native Egyptian Cotton

Crystallinity and crystallite size of eight types of native Egyptian cotton have been measured by the multipeak-resolution method of Hindeleh and Johnson. Remarkable variations in crystallinity were found—it ranges between 69 and 53%—while the crystallite size normal to the 002 planes ranges between 4.1 and 3.6 nm. A sample that possesses higher values of crystallinity and birefringence is characterized by higher values of breaking tenacity and stiffness and by a lower value of breaking elongation. The finest fiber (Guiza 45) has the best structural parameters and tensile properties. Although the crystallinity and birefringence are highly correlated with the physical properties, the birefringence correlation is more significant.

Mercerization of cellulose: 2. The morphology of Mercerized cotton cellulose

Mercerized cotton cellulose has been shown to consist of flexible microfibrils which are similar in dimension to the stiff microfibrils of native cotton. The Mercerized cotton microfibrils are smooth and completely different in appearance from the shish-kebab structures observed by Chanzy and Roche for Mercerized Valonia cellulose. Ultrasonic treatment shows that the Mercerized cotton microfibrils consist of an interconnected fibrous network. The fibrous units comprising this network have widths in the range 20 to 100 Å and appear to be very flexible, in contrast to the stiff 35 Å wide elementary fibrils found in native cotton. A possible mechanism for the Mercerization of cotton is discussed in terms of the rearrangement of sheets of cellulose chains, resulting in crystallites of extended antiparallel chains.

Some Interactions of Water-Soluble Solutes with Cellulose and Sephadex

Elution of a variety of types of water-soluble solutes from gel-permeation columns of chopped native cotton and of Sephadex G-15 was studied. Evidence was obtained concerning (a) the fraction of internal water that is available as solvent water for selected types of solutes, (b) the sorption of strong donor and acceptor hydrogen-bonding solutes on cellulose and Sephadex surfaces, and (c) negative sorption (or repulsion) of carboxyl-containing solutes.

30—THE EFFECT OF THERMAL TREATMENT ON THE CRYSTALLOGRAPHIC ORDER OF NATIVE AND MERCERIZED COTTON

This paper describes a quantitative X-ray-diffraction investigation into the effects of the time of heating native and mercerized cotton fibres at 220°C on the crystallographic order. It is concluded that thermally induced structural modifications are time-dependent and that dissimilar mechanisms operate in the two specimens examined. For example, it appears that an initial recrystallization occurs in native fibres, whereas in mercerized specimens degradation of order increases continuously with the time of heating.

Urea Phosphoric Acid as a Quality-Control Reagent for the Poly-Set Process

Native cotton was modified with methylated methylolmelamine in combination with dimethyloldihydroxyethyleneurea by a two-step treatment similar to that of the Poly-Set process. Physical properties were determined before and after urea phosphoric acid (UPac) hydrolysis to determine if the stripping action of UPac could be used in quality control in the Poly-Set process. UPac does provide a means of correcting treatment errors occurring at any stage of the Poly-Set treatment.

Numbers of Bollworms, Tobacco Budworms, and Cotton Leafworms Caught in Traps Equipped with Fluorescent Lamps of Five Colors123

In field survey experiments in southern Texas and on the isle of St. Croix, V.I., most bollworms, Heliothis zea (Boddie), native or laboratory-reared, preferred traps equipped with BL lamps over traps equipped with green, gold, pink, or white fluorescent lamps. Most native tobacco budworms, H. virescens (F.), and cotton leafworms, Alabama argillacea (Hubner), were attracted to green lamps, but on St. Croix, catches of laboratory-reared tobacco budworms (but not native tobacco budworms) in BL traps were about twice as high as those in traps with green lamps. Catches of nuisance species (large beetles that mutilate light trap collections) were substantially reduced in traps with green lamps, thus identification of economically important lepidopteran species was more reliable. Green lamps may be recommended for survey of low density populations of native tobacco budworms and cotton leafworms, but BL is recommended for survey of bollworms.

Liquid Ammonia vs. NaOH Mercerization as Pretreatment for the Cotton- Butadienediepoxide Reaction. Spectral and Microscopical Studies

Native, mercerized, and ammonia-treated cottons were reacted with butadienediepoxide (BDO), and their fine struc tural changes were followed by x-ray diffractograms, infrared absorption spectra, refractive indices, and in micro scopical cross sections. Conventional mercerization and liquid NH3 pretreatment of native cotton generally produced a more isotropic fiber. But the nature and mode of decomposition of cellulose swelling complexes formed with either NaOH or liquid NH3 differed, as evidenced by differences in crystalline lattices and the optical properties of reaction products. Optical density increased only in the direction of the fiber axis with NH3 but also perpendicularly to the fiber axis with NaOH. Subsequent treatment of NH3-cellulose controls with mercerizing strength NaOH converted their crystalline lattices to Cellulose II. BDO reaction and postmercerization affected the refractive index only in the direction of the fiber axis (η||). Generally, BDO reaction reduced η|| of all but the NH3-cellulose I control; and postmercerization further reduced η|| of only BDO-reaction products that retained the cellulose I lattice. Birefringence of postmercerized BDO-reaction products derived from NH3-cellulose I was lower than that of comparable BDO-reaction products from conventionally mercerized cotton. Before and after BDO reaction, cross sections of most fibers in reaction products from native and NH3-treated cottons with the cellulose I lattice were elliptical, while comparable cross sec tions from conventionally mercerized cotton were round. Changing the catalyst from 2% to 15% NaOH generally increased the number of circular fibers in BDO-treated cottons having the cellulose I structure. All control cottons dissolved in cupriethylenediamine, but BDO-reaction products were insoluble and cross sections appeared solid. Gen erally, reaction products from cottons pretreated with liquid NH3 had a softer hand and dyed more uniformly than did comparable products from conventionally mercerized cotton.

Studies on the root rotting fungus Pyrenochaeta lycopersici: the cellulase complex and regulation of its extracellular appearance

The pathogenic fungus Pyrenochaeta lycopersici, when grown on a medium containing insoluble cellulose as the sole carbon source, selected an extracellular cellulase which slowly solubilized native cotton fibre and rapidly cleaved soluble cellulose derivatives; a β-glucosidase was also synthesized intracellularly. The pH, temperature and substrate concentration of the medium had less effect on the rate of cellulase synthesis than on fungal growth rate. The addition of glucose at concentrations above 0·001 m to cultures containing insoluble cellulose completely repressed synthesis of the cellulase system, although the growth rate of the fungus was enhanced. When cellobiose was used as the sole carbon source less cellulase production occurred than with insoluble cellulose. The data suggest that the production of the enzyme complex in P. lycopersici is controlled by an inducer: repressor mechanism.

Grafting of formaldehyde‐crosslinked and cyanoethylated cotton cellulose with acrylate monomers

AbstractFormaldehyde‐crosslinked cotton and cyanoethylated cotton were grafted with methyl, ethyl, and n‐butyl acrylates and methyl methacrylate using ceric ion as initiator. It was observed that the graft yields for formaldehyde‐crosslinked cotton were significantly higher than those for native cotton. An increase in the bound formaldehyde resulted initially in a decrease in molecular weight of grafts; but later on, an increase was observed. In the case of cyanoethylated cottons, increasing the degree of substitution resulted in increase in graft yields. Molecular weights of the grafts increase up to a D.S. of 0.3, after which they decrease. These results are interpreted in terms of rates of initiation and termination being influenced by production of additional sites due to swelling of cellulose fibers.

Urea-Phosphoric Acid Hydrolysis of Cotton Modified with N-Methylolated Ethylene Ureas

Native and mercerized cotton cellulose, modified with N-methylolated derivatives of ethylene urea, were examined before and after urea-phosphoric acid hydrolyses. Fine structural changes accompanying chemical reactions were evaluated by infrared absorption spectroscopy, x-ray diffraction, and electron microscopy. Final fabric properties and extent of restoration of original tensile properties after urea-phosphoric acid hydrolysis varied with the reagent applied and the lattice structure of the cotton control.

Chlorination and phosphorylation of cotton cellulose by reaction with phosphoryl chloride in N,N-dimethylformamide

Native cotton yarn reacts rapidly with phosphoryl chloride in N,N-dimethylformamide to produce highly chlorinated cellulose (degree of substitution of 0.5 or greater), phosphorylated cellulose, and cellulose formate. The ratio of chlorination to phosphorylation was readily controlled by varying the concentration of phosphoryl chloride in N,N-dimethylformamide. Reaction variables studied were the reagent concentration, reaction temperature, and reaction time. The effect that each of these variables has on the tensile and flammability properties of the resultant yarns was investigated. Yarns containing large proportions of chlorine have high tensile-strength and are unusually extensible, whereas yarns containing phosphorus have high flame-resistance. A mechanism for the selective chlorination or phosphorylation of the cotton cellulose is advanced.

The initial stages of the heterogeneous degradation of alkali cellulose by oxygen in relation to the morphology of native cotton cellulose

AbstractTreatment of cotton cellulose with sodium hydroxide solutions of varying concentration over extended periods in the absence of oxygen markedly decreases the intrinsic viscosity of both the cellulose in cuoxam and its cellulose trinitrate derivative (CTN) in acetone. Light‐scattering measurements show that the molecular weight does not change while the radius of gyration decreases and the second virial coefficient increases. The narrow molecular weight distribution of the native cotton is still maintained. Mild oxidation first causes the intrinsic viscosity to increase. At more prolonged oxidation times the viscosity decreases. These results are interpreted by an intramolecular cross‐linking reaction in the folded cellulose chains with the formation of chemically resistent bonds. Cleavage of the resultant cyclic structures leads to molecules with a larger radius of gyration but the same molecular weight.

Urea-Phosphoric Acid Hydrolysis of Mercerized Cotton Modified with Methylated Methylolmelamine

Mercerized cotton finished with a methylated methylolmelamine (MeMM) responded differently to hydiolysis with urea-phosphoric acid (UPac) than did similarly finished native cotton. UPac hydrolysis did not affect dry and wet wrinkle recoveries of mercerized cotton, but caused reduction in dry recovery angles of the unmodified native cotton control. Treatment with MeMM produced specimens with equally high dry and wet wrinkle-recovery angles regardless of nature of the control fabric; behavior of MeMM-treated fabrics, when subjected to UPac hydrolysis, was influenced by nature of the control fabric. With MeMM-treated mercerized fabrics, each subsequent hydrolysis removed about one-half of the bound nitrogen and virtually all formaldehyde; it destroyed dry recoveries, but had little effect upon wet wrinkle-recovery angles. Each MeMM retreatment completely restored these properties in products from mercerized cotton, but resulted in only partial restoration of recoveries in products from native cotton. X-ray diffractions after MeMM-UPac treatments of mercerized cottons indicated retention of the mixed cellulose I and II lattice of the unmodified control while products from native cotton retained the cellulose I lattice. Infrared spectra indicated that reaction, with MeMM in both cases, proceeded with loss of adsorbed water and occurred preferentially at the primary hydroxyl of cellulose. Unlike products from native cotton, modified mercerized fabrics did not show a buildup of polymer on the periphery of fiber cross sections after an increasing number of MeMM-UPac treatments. Hence, homopolymerization was not indicated in the MeMM treatment of mercerized fabrics.

Crystalline character of native and chemically treated egyptian cottons. II. Computation of variance of x‐ray line profile and paracrystalline lattice distortions

AbstractA variance range analysis of the x‐ray line profiles for seven cottons (native, ureatreated, and mercerized) has been carried out to get two estimates of the crystallite size from (1) the slope and (2) the variance intercept. Assuming the crystallite length of cellulose to be the same in ramie and native cottons under ideal conditions of growth, the relative fluctuation of the repeat length along the b‐axis has been calculated for all the samples. This degree of paracrystalline lattice distortions is negatively correlated with the fiber bundle strength at zero gauge and appears to be the same as the imperfections referred to in the weak link theories of fiber strength. While the orientation parameters are also well correlated with strength, the degree of crystallinity does not seem to have any influence. Wilson's rigorous mathematical treatment of the number‐average particle size, in relation to the two estimates from the variance slope and intercept as well as the particle size distribution, has been successfully applied for the first time to cotton fibers leading to a clearer understanding of crystallite size–strength relationship.

The availability of hydroxyl groups in native and mercerized cotton celluloses

AbstractThe accessibilities of the hydroxyl groups of the D‐glucopyranosyl units of slack mercerized grey yarn and of the same yarn restretched to its original length are compared with those of the original grey yarn, a purified printcloth, and a hydrocellulose. The study involved reactions of the celluloses with N,N‐diethylaziridinium chloride under conditions which ensure minimum conversion of the reagent by hydrolysis to 2‐hydroxyethyldiethylamine. Amylose was taken as a reference material in which the hydroxyl groups are assumed to be completely accessible. Selective accessibilities of the hydroxyl groups at C‐6 and C‐3 relative to those at C‐2 were determined with the same reagent by a method whose development has been described earlier. The results of this study are expressed as fractions of the hydroxyl groups at C‐2, C‐3, and C‐6 that are accessible to the reagent.

Nature of the Swollen State as Determined from Tensile Properties After Cross-Linking

Changes in internal fiber structure of cotton during swelling and tensioning were determined from the effects of these changes on physical properties imparted by cross-linking with dimethylolethyleneurea (DMEU). Cotton yarns were swollen with various agents and subjected to tension during swelling and subsequent washing. Dimethyl sulfoxide (DMSO), aqueous benzyltrimethylammonium hydroxide (BTOH), and solutions of KI and KCNS in NaOH were used as swelling agents. The effect on structure caused by repeated cycling between slack and original length during the base-swollen stage was judged from the effect of subsequent low-level cross-linking on physical properties. Resin pickup and distribution in the yarns were controlled by high-speed centrifugation. The type and concentration of swelling agent are related to the form and degree of tension needed during the swelling steps to produce optimum properties after cross-linking. Improvement of physical properties after cross-linking was found to correlate with increased crystallite orientation over a part of the range studied. The relationship between degree of conversion of native cotton to Cellulose II and energy-to-rupture values is discussed. The characteristic features of low- level cross-linking previously observed in the fiber fragmentation patterns of yarns treated with DMEU, centrifuged to a low wet pickup, and cured, were also seen in the samples repeatedly swollen and restretched prior to DMEU treatment, centrifuging, and curing.

Graft copolymerization of vinyl monomers on modified cottons—I: Grafting of vinyl monomers on partially carboxymethylated cotton

Grafting of partially carboxymethylated cotton (PCMC) with acrylonitrile (AN), methyl methacrylate (MMA) and acrylamide (AA) was effected using Ce IV as initiator. Under similar reaction conditions, the graft yield increased by increasing the degree of substitution of PCMC up to 0·124, beyond which the grafting decreased. However, the graft yields for PCMC were significantly higher than those for native cotton and cotton treated with sodium hydroxide. Reactivities of monomers were in the order AN > MMA > AA. Increasing the monomer concentration caused a substantial increase in the graft yields. The same effect was found with initiator up to a certain concentration but, beyond it, there was a reversal. The Ce IV consumption during grafting increased with rising concentration of Ce IV, but decreased with rising monomer concentration. Comparison of Ce IV consumption during grafting and oxidation showed that their magnitudes depend on the nature of the substrates, monomer and initiator as well as the reaction conditions. Grafting had practically no effect on the carboxymethyl (expressed as carboxyl groups) of modified cotton.

Cellulase and (β-Glucosidase Components in Culture Filtrates fromBotryodiplodia theobromaePat.

Cellulase and /3-glucosidase components in culture filtrates from Botryodiplodia theobromae Pat. were separated by polyacrylamide-gel electrophoresis and gel-filtration on Sephadex. A correlation between the electrophoretic mobilities and gel-filtration behaviour of the com ponents was established. Four cellulase components (Ca, Cb, Cc, and Cd) were recognized with approximate molecular weights of 162 000 (Ca), 15 000 (Cb), 10 000 (Cc), and 4500 (Cd). Four /3-glucosidase components (Ba, Bb, Be, and Bd) were also recognized with molecular weights of 112 000 (Ba), 56 000 (Bb), 27 000 (Be), and 13 300 (Bd). The cellulase components appeared to be composed of aggregates of similar subunits. Similarly, the /3-glucosidase com ponents appeared to be aggregates of a subunit that differed from the cellulase subunit. The activities of the cellulase components differed on different cellulosic substrates. Cotton flock was readily solubilized by a mixture of cellulase components Ca, Cb, and Cc, an effect which was enhanced in the presence of component Cd. Any appreciable solubilization of native cotton fibres required component Ca or, more effectively, Cd.

Effect of Radial Location of Cross Links in Cellulose Fibers on Fabric Properties

Mercerized cotton fabrics cross-linked preferentially in the core of the individual fibers were prepared by rinsing off part of the DMEU before curing from the peripheral areas with ethanol. Native cotton, due to its pore structure, does not lend itself readily to this technique. This pore structure is also reflected in the dyeability of native cotton from alcoholic dye solution in contrast to the behavior of the mercerized fiber. The core-crosslinked fibers give much higher substitution in carbanilation and benzoylation than uniformly cross-linked fibers of the same content of fixed cross-linking reactant. The fabrics of core-crosslinked cotton exhibit a favorable balance of mechanical properties. Such fabrics were shown, e.g., to possess a dry crease recovery angle of 280° (W + F) and, at the same time, the abrasion resistance equal to that of uncrosslinked fabrics.