Single Fiber Strength Variations of Developing Cotton Fibers—Strength and Structure of G. hirsutum and G. barbedense

Abstract

This paper reports on the single fiber strength and crystalline structure of two cotton fiber species, G. hirsutum (Texas Marker 1) and G. barbedense (Pima S7), at varying developmental stages from 20 days post-anthesis (dpa) to maturity. For both species, the force required to break single fibers increases with fiber development, with the most significant increases occurring during the fourth week of cell development. The patterns of increasing breaking force through the end of the fourth week of fiber development are similar for these two species. As fibers develop beyond 30 dpa, the single fiber breaking force and tenacity of G. barbedense fibers are higher than those of G. hirsutum fibers. Both developing fibers show characteristic cellulose I diffraction patterns. The overall crystallinity and apparent crystallite sizes increase with development for both species. The most significant increases in L 101 , L 101 , and crystallinity occur between 20 and 35 dpa, corresponding to the first two weeks of cellulose synthesis or the fourth and fifth weeks of overall fiber development. Development beyond five weeks does not contribute to any change in crystallite dimensions or crystallinity, consistent with the leveling of tenacity at this later stage of development.The mechanical properties of cotton fibers have been extensively studied and reviewed [9,10]. The strength of cotton has been attributed to fiber structure, including the rigidity and high molecular weight of the cellulose chains, the extensive inter-and intramolecular hydrogen bonding, and the highly fibrillar and crystalline structure of the fibers. Many have attempted to correlate fiber strength with the molecular weight of the cellulose, its crystallinity, and its reversal and convolution characteristics. Most of these fiber strength data have been derived from bundle strength measurements of mature and/or processed fibers. Although fiber bundle strength (by Stelometer measurements) increases gradually with fiber growth [81, much less is known about the single fiber strength of developing cotton fibers.Cotton fibers are single cells that develop over four overlapping but distinct stages: initiation, elongation, secondary wall thickening, and maturation [3]. Following the initiation of fibers from 2 days prior to the day of anthesis, the fibers elongate until reaching their final lengths in about 20 to 25 days. Secondary wall synthesis starts around 15 to 22 days post-anthesis (dpa) and continues for 30 to 40 days. Variations in fiber dimensions, i.e., fineness and length, are genetically related, whereas those associated with fiber maturity are growth-and/or environmentally dependent. Single fiber breaking force depends on both fiber development and drying. Of the four developmental stages, our focus has been from the onset of secondary wall synthesis, which occurs around 15 to 22 days post-anthesis (dpa) and overlaps with the later state of fiber elongation to maturity. Our data on G.hirsutum varieties have shown that fibers at about 21-24 dpa exhibit...

Towards green carbon fibre manufacturing from waste cotton: a microstructural and physical property investigation

“…Dehydration of the cellulosic unit leads to the formation of the double-bonded intermediates [34]. The mass change in fibres starts by lowering the molecular weight [35] and may result in consequently low tensile strength [36]. For temperatures below 300°C, the decomposition proceeded very slowly with only 5 wt.% losses.…”

Analysis of the physical properties of developing cotton fibres

“…Hu and Hsieh [1] studied crystalline structure of developing cotton fibres using wideangle X-ray scattering (WAXS) diffraction and reported that the most significant increase in the degree of crystallinity is between 21 and 34 dpa. Hsieh et al [4] reported that crystallinity occurs between 20 and 35 dpa, and development beyond that does not contribute to any changes in crystallinity. These observations suggest that these analysis techniques could be more sensitive in detecting crystallinity changes early in fibre development than previous studies.…”

“…Secondary cell wall synthesis begins around 15 to 22 dpa and continues for 30 to 40 days. Fibre maturation is evident by a twisted ribbonlike structure beginning 45 to 60 dpa [2,4]. While cells are growing, cellulose is synthesised by the condensation of glucose molecules at enzyme complexes, each of which generates 36 cellulose molecules; these lie in the same direction and crystallise into long microfibrils [5].…”

“…In studies of the crystalline structures of developing cotton fibres, Paralikar [6] showed that the crystalline structure at 5 dpa belonged to cellulose I; Tuichiev et al [7] suggested that immature cotton fibres up to 10 days after flowering showed crystalline structure cellulose III, while the cellulose I was shown only for mature fibres; Chanzy et al [8] noted that cellulose of the primary wall of cotton at 15 dpa possesses the crystalline structure of cellulose IV; Hsieh et al [4,9] and Hu and Hsieh [1,10] demonstrated that crystallinity increases with fibre development; Hsieh et al [4] showed that the most significant increase in crystallinity occurs between 20 and 35 dpa, equivalent to the first two weeks of secondary cell wall synthesis or the fourth and fifth weeks of entire fibre development. It is reported that no change in crystallinity is contributed by development beyond 35 dpa [4].…”

The Effect of Blends between Some Egyptian cotton Varieties and Introduced Cottons on Technological and Spinning Characters

“…Hence blending between the two categories of cotton lint may offer an opportunity to obtain yarns with higher quality than that of upland cotton and of lower prices (Hsien et al, 2000). However, blending of cottons with different quality characteristics may have an effect on fiber characteristics of the blend and resulting yarn quality (Majumdar, 2004 andNomer andAbd El-Hamid, 2005).…”