Quantitative Analysis of Crystalline Phases in Chemically Treated Cotton Fibers

Zheng

et al. 2018

ACS Appl. Nano Mater.

High aspect ratio carboxycellulose nanofibers (NOCNF), having typical length over 1000 nm, width ∼4.6 nm, thickness ∼1.3 nm, and carboxylate content of 0.42 mmol/g, were extracted from jute fibers using a modified nitro-oxidation method. The extracted nanofiber was found to possess crystallinity of 69% (measured by wide-angle X-ray diffraction, WAXD), relatively higher than that of raw jute fibers (crystallinity ∼61%). Gelation of NOCNF in aqueous suspensions was observed due to the high aspect ratio of the fiber even at a relatively low concentration. Rheological studies on the NOCNF suspensions at different concentrations (0.01−1 wt %) revealed the shear-thinning behavior with increasing shear rate. The corresponding viscoelastic moduli (G′ and G′′) results indicated that the NOCNF suspension at concentration between 0.1 and 0.2 wt % possessed a liquid−gel transition. The rheological data near the gelation point could be fitted by the Winter−Chambon model, where the results confirmed the formation of a percolated fibrous network. The flow behavior of the NOCNF suspensions in the chosen concentration range could be further described by the concept of the crowding factor. Nanopaper prepared using these high aspect ratio carboxycellulose nanofibers exhibited good mechanical properties with tensile strength of 108 ± 2 MPa and Young's modulus of 4.1 ± 0.2 GPa.

Section: Resultssupporting

confidence: 62%

Section: CIsupporting

confidence: 65%

High Aspect Ratio Carboxycellulose Nanofibers Prepared by Nitro-Oxidation Method and Their Nanopaper Properties

Zheng

et al. 2018

ACS Appl. Nano Mater.

Textile Research Journal

“…The crystallinity index of the treated fabrics and the powders was obtained by the formula Crl = ( (/12 2 + l2t.s)/2 -~ lll)/(112 + /21.5)/2, where Ix is the intensity measured at x degrees adapted from Cidambareswaran et al [6]. X-ray diagrams were obtained with a Philips analytical PW 1710 diffractometer and an x-ray tube using Ni filtered CuKa radiation.…”

Section: Methodsmentioning

confidence: 99%

Enzymatic Treatment of Lyocell—Clarification of Depilling Mechanisms

Morgado

Cavaco-Paulo

Rousselle

2000

We have characterized cellulose from the original structure of a lyocell fabric, from pills mechanically removed from the surface with a razor blade and from cellulose microfibrils removed from the surface and dispersed in the liquor during a cellulase depilling process. We find that cellulases first attack the cellulose from the microfibrils on the surface of the fabric because they are more externally exposed than the cellulose of the original fabric structure and have the same characteristics in terms of molecular weight, polydispersity, and crystallinity index as the base fabric. Cellulose from the microfibrils removed from the base fabric by the cellulase and recovered from the liquor shows significantly increased polydispersity, therefore indicating that the microfibrils have been widely attacked by the enzymes. Cellulases prove to be thorough surface finishing agents, since they change only the fiber surface, not the crystallinity.

J of Applied Polymer Sci

“…Changes of internal structure 13 The changes in the specimen crystallinity and internal structure as a result of degradation were also investigated by using an X-ray diffractometer (M18XHF-SRA, Mac Science Co., Roswell, GA).…”

Section: Evaluation Of Biodegradabilitymentioning

confidence: 99%

Biodegradability of cellulose fabrics

Park

Kang

2004

188

Biodegradability of cellulose fabrics was evaluated by use of a soil burial test, an activated sewage sludge test, and an enzyme hydrolysis. Surface changes after biodegradation were observed by optical microscopy. From X-ray diffraction analysis (XRD), changes in the crystallinities and the internal structures as a result of degradation were also investigated. It was shown that biodegradability decreased in the following order: rayon Ͼ cotton Ͼ Ͼ acetate. Rayon fibers, which have a low crystallinity and a low degree of orientation, showed the highest biodegradability in most cases. However, in spite of its low crystallinity, acetate fibers exhibited very low biodegradability, probably because of the presence of hydrophobic groups in its structure. On the other hand, linen showed an inconsistent behavior in that it had the highest biodegradability in the soil burial test, but a lower biodegradability than that of cotton in the activated sewage sludge test. XRD analysis revealed that there was a slight increase in the crystallinity of linen, cotton, and rayon fabrics at the initial stage, but a continuous decrease thereafter. From the correlation analysis, it was revealed that the biodegradability of cellulose fabrics was closely related to the moisture regain of the fibers, which reflects the hydrophilicity and internal structure of the fibers at the same time.