Characterization of the crystalline structure of cellulose using static and dynamic FT-IR spectroscopy.
TL;DR: In this work, dynamic FT-IR spectroscopy has been further explored as a method sensitive to cellulose structure variations and had the potential to indicate possible correlation field splitting peaks of cellulose Ibeta.
About: This article is published in Carbohydrate Research.The article was published on 2004-02-25. It has received 355 citations till now. The article focuses on the topics: Cellulose & Pulp (paper).
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TL;DR: Four different techniques incorporating X-ray diffraction and solid-state 13C nuclear magnetic resonance (NMR) were compared using eight different cellulose preparations and it was found that the simplest method, which is also the most widely used, and which involves measurement of just two heights in the X- Ray diffractogram, produced significantly higher crystallinity values than did the other methods.
Abstract: Although measurements of crystallinity index (CI) have a long history, it has been found that CI varies significantly depending on the choice of measurement method. In this study, four different techniques incorporating X-ray diffraction and solid-state 13C nuclear magnetic resonance (NMR) were compared using eight different cellulose preparations. We found that the simplest method, which is also the most widely used, and which involves measurement of just two heights in the X-ray diffractogram, produced significantly higher crystallinity values than did the other methods. Data in the literature for the cellulose preparation used (Avicel PH-101) support this observation. We believe that the alternative X-ray diffraction (XRD) and NMR methods presented here, which consider the contributions from amorphous and crystalline cellulose to the entire XRD and NMR spectra, provide a more accurate measure of the crystallinity of cellulose. Although celluloses having a high amorphous content are usually more easily digested by enzymes, it is unclear, based on studies published in the literature, whether CI actually provides a clear indication of the digestibility of a cellulose sample. Cellulose accessibility should be affected by crystallinity, but is also likely to be affected by several other parameters, such as lignin/hemicellulose contents and distribution, porosity, and particle size. Given the methodological dependency of cellulose CI values and the complex nature of cellulase interactions with amorphous and crystalline celluloses, we caution against trying to correlate relatively small changes in CI with changes in cellulose digestibility. In addition, the prediction of cellulase performance based on low levels of cellulose conversion may not include sufficient digestion of the crystalline component to be meaningful.
2,522 citations
Cites methods from "Characterization of the crystalline..."
...Methods using Fourier transform (FT)-IR spectroscopy determine CI by measuring relative peak heights or areas [10-12]....
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TL;DR: The crystallite size was decreased to constant value for Cell 2 treated at >or= 15 wt% NaOH, and the crystalliteSize of Cell 2-C (cellulose II) was smaller than that of Cell 1 ( cellulose I) treated at 5-10 wt%, and the CI(XD) was calculated by the method of Jayme and Knolle.
1,113 citations
TL;DR: The decrease of HBI, the easy removal of DMAc, and the band at 1593cm(-1) supported the introduction of new chemical structure in cellulose.
743 citations
TL;DR: The results showed that higher extractive contents associated with lower crystallinity and lower cellulose crystallite size can accelerate the degradation process and reduce the thermal stability of the lignocellulosic fibers studied.
Abstract: In this work, the relationship between cellulose crystallinity, the influence of extractive content on lignocellulosic fiber degradation, the correlation between chemical composition and the physical properties of ten types of natural fibers were investigated by FTIR spectroscopy, X-ray diffraction and thermogravimetry techniques. The results showed that higher extractive contents associated with lower crystallinity and lower cellulose crystallite size can accelerate the degradation process and reduce the thermal stability of the lignocellulosic fibers studied. On the other hand, the thermal decomposition of natural fibers is shifted to higher temperatures with increasing the cellulose crystallinity and crystallite size. These results indicated that the cellulose crystallite size affects the thermal degradation temperature of natural fibers. This study showed that through the methods used, previous information about the structure and properties of lignocellulosic fibers can be obtained before use in composite formulations.
664 citations
Cites background from "Characterization of the crystalline..."
...The band at around 1420–1430 cm −1 is associated with the amount of the crystalline structure of the cellulose, while the band at 898 cm −1 is assigned to the amorphous region in cellulose [6]....
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TL;DR: In this article, the progress and applications of infrared techniques in biomass study, and compares the infrared and the wet chemical methods for composition analysis, are summarized and compared, in addition to reviewing recent studies of biomass structure and composition.
645 citations
Cites methods from "Characterization of the crystalline..."
...In addition, dynamic FTIR was used to study cellulose allomorph I composition in pulp samples [97]....
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References
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Book•
01 Jan 1964
TL;DR: Theoretical analysis of molecular vibrational and rotational spectra has been studied in this paper, with a focus on the Vibrational Origin of Group Frequencies (VIB).
Abstract: Vibrational and Rotational Spectra. IR Experimental Considerations. Molecular Symmetry. The Vibrational Origin of Group Frequencies. Methyl and Methylene Groups. Triple Bonds and Cumulated Double Bonds. Olefin Groups. Aromatic and Heteroaromatic Rings. Carbonyl Compounds. Ethers, Alcohols, and Phenols. Amines, C=N, and N=O Compounds. Compounds Conking Boron, Silicon, Phosphorus, Sulfur, or Halogen. Major Spectra-Structure Correlations by Spectral Regions. The Theoretical Analysis of Molecular Vibrations.
5,173 citations
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01 Jan 1999
TL;DR: Collecting together aspects of the chemistry of natural products, this work was conceived as a source of the underlying general principles governing modern natural products physics as discussed by the authors, and was used as a basis for the present paper.
Abstract: Collecting together aspects of the chemistry of natural products, this work was conceived as a source of the underlying general principles governing modern natural products physics
1,145 citations
TL;DR: Multiplicities in the resonances of chemically equivalent carbons, which appear in the solid-state carbon-13 nuclear magnetic resonance spectra of native celluloses, have been examined at high resolution and are consistent with the existence of two distinct crystalline forms.
Abstract: Multiplicities in the resonances of chemically equivalent carbons, which appear in the solid-state carbon-13 nuclear magnetic resonance spectra of native celluloses, have been examined at high resolution. The patterns of variation are consistent with the existence of two distinct crystalline forms. One form is dominant in bacterial and algal celluloses, whereas the other is dominant in celluloses from higher plants.
1,092 citations
01 Jan 1992
TL;DR: In this article, the authors describe the common liquid sampling accessories and applications of solution state FTIR spectroscopy to lignins, and the reader is referred to Chapter 4.1.
Abstract: Typically, lignins are characterized by IR spectroscopy in the solid state. The examination of lignins in solution has long been a domain of UV and NMR spectroscopy. However, with the advent of the FTIR technique, the IR spectra of liquid samples now can be readily obtained. The need to measure IR spectra in solution exists when there is not enough time to isolate lignin from solution as, for example, is the case when spent pulping liquors have to be analyzed rapidly during a pulping process for process control. This section describes briefly the common liquid sampling accessories and applications of solution state FTIR spectroscopy to lignins. For more details on FTIR spectroscopy, the reader is referred to Chapter 4.1.
1,024 citations
TL;DR: In this paper, a new infrared ratio, α1372 cm.−1/α2900 cm−1, is proposed for measuring crystallinity in cellulosic materials, which can be applied to both celluloses I and II and, therefore, to samples containing a mixed lattice.
Abstract: A new infrared ratio, α1372 cm.−1/α2900 cm.−1, is proposed for measuring crystallinity in cellulosic materials. The advantage of this ratio over others which have been used is that it can be applied to both celluloses I and II and, therefore, to samples containing a mixed lattice. Two series of samples, encompassing a wide range of crystallinity, were prepared from highly crystalline celluloses I and II. The infrared ratios of these samples were compared with crystallinity values from x-ray diffractograms and density measurements, and with accessibility data from moisture sorption. It was shown that the new infrared ratio ranks samples of both lattice types, as well as partly mercerized cottons, in the same order as do x-ray, density, and moisture sorption data. The correlation of the new infrared ratio with accessibility, derived from moisture regain, is better than with crystallinities from either x-ray or density measurements. Reasons for this are suggested.
797 citations