X-ray Crystallinity of Bleached and Crosslinked Cottons

Abstract

It has long been recognized through X-ray diffraction (and other techniques) that cellulose is part crystalline and part amorphous (semicrystalline) [1]. In the crystalline (ordered) regions the cellulose chains are held in mutual H-bonding, whereas the cellulose chains do not form hydrogen bonding in the amorphous (disordered) regions. In other words, large numbers of cellulosic hydroxyl groups are available for modification. During the physical and chemical treatments, these hydroxyl groups in the amorphous regions are modified, resulting in changes in swelling and percentage crystallinity.For native cotton cellulose, portions of the fiber are arranged in an orderly fashion or lattice. The fundamental unit to make up this lattice is referred to as the unit cell. A diagram of this unit cell, as derived by Meyer and Misch [2], is reproduced in Figure 1. The cell is a monoclinic with three principal planes of reflection shown as (002), (101), and (101).Using x-ray diffraction, Sarna and Wlochwicz [3] determined that the crystallinity index (CI) of raw cotton from Uzbekistan and Turkmenistan was in the range of 73-78% and that the CI values increased with growth in the maturity of cotton fibers. These CI values were similar to those obtained by other researchers [4, 5]. 1 2 3 A setup of a continuously recording X-ray diffractometer is shown in Figure 2(a) and that of a plot of the angular dependence of the intensity of X-ray photons as a function of 2θ in Figure 2(b). The three peaks for native cotton Cellulose I are (101) at 2θ = 14.9 o , (101) at 2θ = 16.6 o and (002) at 2θ = 22.7 o . Segal and Conrad and Segal et al. [6, 7] developed an empirical method for estimating the degree of crystallinity of native cellulose (Cellulose I). The amount of crystallineAbstract An X-ray diffractometer was used to study the crystalline structure of cotton fibers after bleaching, crosslinking and a combination of bleaching and crosslinking treatments. Wet crosslinking was accomplished with formaldehyde (Form W) and dry crosslinking was carried out with either dimethyloldihydroxyethyleneurea (DMDHEU) or citric acid (CA). Results indicated that crosslinking of bleached cotton did not change the crystalline nature of cotton (i.e. it was Cellulose I), but did increase its degree of crystallinity when crosslinked with either DMDHEU or CA; crosslinked formaldehyde (Form W) was relatively less crystalline.

Preparation and catalytic performance of Fe(III)-citric acid-modified cotton fiber complex as a novel cellulose fiber-supported heterogeneous photo-Fenton catalyst

“…A fitting of a high-resolution C1s spectrum into three Gaussian peaks is also shown Cellulose XRD analysis Figure 4 shows the XRD patterns of cotton fiber before and after modification and coordination. Three typical characteristic peaks of cotton fiber were found at 14.50°, 16.72°and 22.81°, which agreed well with those published in the literature (Parikh et al 2007). It was worth noticing that the peak centered at 22.81°h ad a strong intensity after the modification, indicating that treatment with citric acid increased the crystallinity of cotton fiber.…”

“…This is because the citric acid molecule can penetrate the amorphous regions in the fiber more easily than it does the crystals when cotton fiber is modified with citric acid. Then they produce crosslinks between the cellulose units in the amorphous regions, thus increasing the crystallinity (Xu 2003, Parikh et al 2007). However, the intensity of this peak was reduced by subsequent coordination of Fe(III) ions.…”

“…Besides, the highest Q Fe was found when C CA was 10.0 % (w/w), and further increasing C CA led to a reduced Q Fe . This can be explained by the fact that the modified cotton fiber with an excessive concentration of citric acid may have become more crystalline and less amorphous (Parikh et al 2007), which inhibits the penetration and diffusion of the Fe(III) ion aqueous solution into CA-Cotton, thus retarding the reaction between them. More importantly, Table 1 shows that the higher C CA gave rise to an increment in both D% and k, and there is an optimum C CA level [about 10.0 % (w/w) in this test].…”

Polypyrrole-coated cotton fabrics for flexible supercapacitor electrodes prepared using CuO nanoparticles as template

“…Figure 4 presents the X-ray diffraction (XRD) pattern of the PPy-coated samples (S0 and S1). It is (Parikh et al 2007), while the XRD pattern of PPy displays only an amorphous feature of 2h between 20°and 30°(Firoz Babu et al 2013). Here the three peaks are also found for both the S0 and S1 fabrics.…”

Extraction and Characterization of Fibres from the Stalk and Spikelets of Empty Fruit Bunch

“…Both stalk and spikelet-derived material shows a very broad peak at about 17 ∘ and a relatively strong and sharp peak at 22.1 ∘ . The broad peak at 2 angle 17 ∘ is probably due to amorphous cellulose or the overlapping of the (101) and reflections [39], while the peak at 2 of 22.1 ∘ is assigned to the strong (200) reflection of cellulose [36,[40][41][42]. The diffractogram of spikelet-derived cellulose shows additional sharp peaks, including one at 2 reflection angle of 35 ∘ .…”