Novel Terahertz Spectroscopy Technology for Crystallinity and Crystal Structure Analysis of Cellulose

Abstract

Crystallinity is an essential indicator for evaluating the quality of fiber materials. Terahertz spectroscopy technology has excellent penetrability, no harmful substances, and commendable detection capability of absorption characteristics. The terahertz spectroscopy technology has great application potential in the field of fiber material research, especially for the characterization of the crystallinity of cellulose. In this work, the absorption peak of wood cellulose, microcrystalline cellulose, wood nano cellulose, and cotton nano cellulose were probed in the terahertz band to calculate the crystallinity, and the result compared with XRD and FT-IR analysis. The vibration model of cellulose molecular motion was obtained by density functional theory. The results showed that the average length of wood cellulose (WC) single fiber was 300 μm. The microcrystalline cellulose (MCC) was bar-like, and the average length was 20 μm. The cotton cellulose nanofiber (C-CNF) was a single fibrous substance with a length of 50 μm, while the wood cellulose nanofiber (W-CNF) was with a length of 250 μm. The crystallinity of cellulose samples in THz was calculated as follows: 73% for WC, 78% for MCC, 85% for W-CNF, and 90% for C-CNF. The crystallinity values were obtained by the three methods which were different to some extent. The absorption peak of the terahertz spectra was most obvious when the samples thickness was 1 mm and mixed mass ratio of the polyethylene and cellulose was 1:1. The degree of crystallinity was proportional to the terahertz absorption coefficients of cellulose, the five-movement models of cellulose molecules corresponded to the five absorption peak positions of cellulose.

Cellulose Extraction From Green Algae, Ulva Ohnoi, and Its Application to PVA‐Based Antibacterial Composite Films Incorporated With Zinc Oxide Nanoparticles

“…The peaks at 2θ = 15.1°, 22.4° and 34.5° were attributed to the (100), ( 200) and (004) crystalline plane of Cellulose I [27]. However, the peak related to the (004) crystalline plane of Cellulose I in the spectrum of the EC was too weak, which agrees with a report by Yang et al [28] The low intensity of the (004) crystalline plane of Cellulose I in EC is due to its low crystallinity [23].…”

Thermally resistant and strong shape memory bismaleimide resin with intrinsic halogen‐free and phosphorus‐free flame retardancy

“…Reviewing the literatures in the SCI database by June 6, 2022, there are 19 articles related on flame retardant SMPs including thermoplastics and thermosets (Table S1), 5–23 from which three problems are generally found. First, most SMPs get their flame retardancy from phosphorus‐related flame retardants, however, phosphorus‐related flame retardants have been reported to cause eutrophication of the water bodies 24 ; moreover, they also tend to degrade thermal stability of thermally resistant resins 25,26 .…”

First principles terahertz spectroscopy of molecular crystals: the crucial role of periodic boundary conditions benchmarked with experimental l-ascorbic acid spectra

“…6,7 Moreover, because of the high sensitivity to intra- and inter-molecular structures, THz spectroscopy has a fingerprint characteristic, which is effective in the detection of isomers and other similar substances. 8–10 These unique properties inspire the wide use of THz spectroscopy in the detection of various substances, e.g. , high energy explosives, 11–13 drugs, 14–16 poisons, 17,18 etc.…”

“…6,7 Moreover, because of the high sensitivity to intra-and intermolecular structures, THz spectroscopy has a fingerprint characteristic, which is effective in the detection of isomers and other similar substances. [8][9][10] These unique properties inspire the wide use of THz spectroscopy in the detection of various substances, e.g., high energy explosives, [11][12][13] drugs, [14][15][16] poisons, 17,18 etc. For better application of THz spectroscopy in fundamental science and industrial non-destructive testing, it is important to correctly assign the THz spectral signatures, which must resort to theoretical modelling, e.g., quantum chemical calculations.…”