SynopsisAn electron-microscopic diffraction technique has been described to record with ease diffraction patterns of cotton cellulose with 3-5 sec exposure time, which is suited to determine the crystallinity of cellulose. The % crystallinity index for cotton and ramie determined by this technique amounted to 81% and 85%, respectively.

SynopsisThe lateral order factor of four Indian varieties of silk, viz., Mulberry, Tasar, Eri, and Muga, were determined by electron diffraction technique and compared with that determined by x-ray diffraction. The profiles of the 002 and 201 reflections in Mulberry were better resolved by the electron diffraction technique. INTRODUCTIONStructure investigation of silk fibroin has been carried out by many workers using different techniques such as x-ray diffraction,1,2 infrared spectroscopy,3 amino acid a n a l y~i s ,~ and electron microscopy.5.6 Detailed x-ray diffraction studies by Marsh et al.1.7 and Warwicker2 have established that fibroin has a parallel P-type structure. The unit cell proposed by these workers is orthorhombic. Magoshi et al.8.9 have studied the a-p transition of regenerated silk obtained from the glands of mature silkworms. Recently, studies have been made on synthetic poly(a-amino acids) using x-ray and electron diffraction techniqueslOJ1 to elucidate elaborately with models the structure of silk fibroin. However, electron diffraction has not been used extensively for structure investigation of the silk fibroin. In this paper, we report the electron diffraction results obtained for different varieties of Indian silk. EXPERIMENTAL MaterialsMulberry (Bombyx mori), Tasar or Tussah of India (Antheraea mylitta), Eri (Philosamia Cynthia ricini), and Muga (A. assamensis) silks were used for the studies. Mulberry silk yarn was degummed by treating with textile soap a t 100°C for 1 hr with a materia1:liquor ratio of 1:50. The sample was washed with hot and cold water and finally dried under vacuum. The wild silk yarns were degummed by treating with textile soap in the presence of washing soda (0.5 gh.) a t 100°C for 1 hr with a materiakliquor ratio of 1:50. The sample was rinsed with hot and cold water. The degumming was repeated.12 * Part of this work was presented a t the XIth Annual Conference of EMS1 held a t Madras, India, Equipment and ProcedureThe electron diffraction technique employed was essentially the same as that described by Paralikar and Betrabet.'" The silk filaments were thoroughly beaten in a high-speed laboratory blender. A drop of diluted slurry of silk fragment was placed on uncoated 400-mesh copper grid and dried at room temperature. A Hitachi HU 11E electron microscope was used. The experimental conditions were, in brief use of liquid nitrogen throughout the experiment to cool the specimen, accelerating potential of 75 kV with extremely lowbeam current, and exposure time of 5 sec. Before examining the silk specimen, a grid supporting thin film of A1 was inserted in the microscope and the microscope was preset in the diffraction mode and focused to get a sharp typical A1 pattern. This served two purposes. The camera constant could be determined and scanning of grids supporting silk specimen in the bright-field transmission mode was avoided, thereby minimizing to the utmost any degradation owing to the electron beam. Then grid supporting the A1 film was replaced by the grid su...

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Electron micrographs are presented of cotton cellulose treated with aqueous solutions of the inter-and intracrystalline swelling agents, morpholine, piperidine, piperazine, ethylenediamine, and zinc chloride. The concentration of each swelling agent was such as to produce maximum recoverable swelling of cotton cellulose. Physical and fine-structure characteristics of these treated cottons, after complete removal of the swelling agent, revealed that morpholine and piperidine are intercrystalline and piperazine, ethylenediamine, and zinc chloride are intracrystalline swelling agents. Thisw as confirmed by electron-microscope determination of microfibrillar morphology and dimensions. The layer-expansion technique was used to examine these treated cottons along with samples that had been treated with sodium hydroxide and phosphoric and sulfuric acids. The electron micrographs revealed marked gradation in swollen and decrystallized cottons, which may serve as a visual scale at the microfibrillar level for cotton decrystallized to varying degrees. To confirm the extent to which the morphology of decrystallized cotton observed by the layer-expansion technique really exists in the swollen state before the removal of the swelling agent, the cottons treated with sodium hydroxide, morpholine, zinc chloride, and sulfuric acid were embedded in glycol methacrylate in the swollen state and the ultrathin cross sections of these were examined.

synopsisCotton fiber was treated with aqueous trimethylbeneylammonium hydroxide (Triton B) at concentrations over the range 25%4oY0. 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 320/, 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 I1 at 35% and 4Oy0 Triton B concentrations. The results indicate that, used a t the critical concentration of 30%, Triton B can be a useful swelling agent for cotton fibers BS it opens up the fine structure of cellulose considerably without impairing any important physical properties.