P. Bhama Iyer

Influence of delignification and alkali treatment on the fine structure of coir fibres (Cocos Nucifera)

The present communication reports the effect of a softening treatment carried out with 18% NaOH on the fine structure and structure-property relations in coir fibres. The effect of successive removal of lignin and hemicelluloses on the fine structure has also been studied. Unlike other cellulosic fibres, alkali treatment failed to produce any increase in fibre elongation in coir. However, the spiral structure was found to be considerably modified by swelling. X-ray and infrared spectral measurements revealed that a part of the noncellulosic components does occupy the intracellular space and plays a significant role on fine structural changes produced during the alkali treatment.

Crystallization of Amorphous Cellulose

Recrystallization behavior of the hydrolysates of native and thrice mercerized cotton, ball-milled to yield samples of different amorphity, was studied using x-ray diffraction. For crystallization of amorphous cellulose into cellulose I lattice, the presence of cellulose I nuclei seems to be a prerequisite. In a partially ball-milled cellulose I . sample, crystallization into cellulose II does not start until the amorphous content is as high as 75% or more. Results are discussed on the basis of the current ideas of the fine structure of fibers.

Reversals in Cotton: A Study with Scanning Electron Microscopy

The fibrillar morphology of the reversal zones in cotton fibers swollen in aqueous zinc chloride (ZnCl 2) is examined using scanning electron microscopy. There are dis tinct differences in the size of fibrillar aggregates on the two sides of structural reversals in some of the ZnCl2 treated fibers in all four varieties of cotton studied. These dif ferences seems to suggest that fibrils flanking a structural reversal could differ in their fineness levels.

Recrystallization of Cellulose

Hydrolysates of fibers swollen in various intracrystalline swelling agents were ball- milled for separate periods. These samples containing different proportions of cellulose I (C I) Cellulose II (C II) and amorphous (Am) phases were subjected to a mild hy drolysis, and their recrystallization behavior was studied by x-ray diffraction methods. Recrystallization into C I occurs only by nucleation, whereas recrystallization into C II is also caused by accretion of the long disordered molecular segments severed from crystallites.

Extraneous Lattice in Regenerated Cellulose

Hydrolysis of regenerated celluloses under suitable conditions and after suitable pretreatments leads to well defined x-ray diffraction patterns compared to the poorly defined patterns of the parent samples. X-ray diffraction diagrams obtained after hydrolysis indicate clearly that regenerated celluloses contain an extraneous lattice in addition to cellulose II. The major extraneous lattice in normal viscose and high wet modulus rayon is cellulose I, while that in high tenacity rayon is cellulose IV.

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

attention, although it has been observed by x-ray methods that these variations are only marginal [1,8]. In a recent paper, however, Hindeleh [3], employing a modified x-ray diffraction procedure, has reported that differences do exist in the crystallinity of cotton varieties, and that crystallinity is correlated with fiber properties like tenacity, extensibility, and fineness. The observations are based on data from eight vari-

Milling of Partially Mercerized Cellulose

(positive or negative) are due to circumstances independent of the studied phenomenon. For open-end spun yams, all results are positive and high, showing the existence of a systematic trend similar to that previously encountered for acrylic staple openend spun yams [2]: the apparent loss of twist increases when twist increases and when linear density grows. The blend composition as well as the nature of the opening roller clothing seems to influence the amount of the apparent loss of twist. If we then compare these results with those from acrylic staple rotor-spun yarn experiments [2], we obtain the numbers in Table II. These data show that the apparent loss of twist depends on many factors, including fiber type, blend percentage, machine and spinning process parameters, and yarn characteristics.