Effect of mercerization on the crystallite size and crystallinity index in cellulose from different sources

1987 ◽  
Vol 65 (8) ◽  
pp. 1724-1725 ◽  
Author(s):  
J. F. Revol ◽  
A. Dietrich ◽  
D. A. I. Goring
Keyword(s):  
Sodium Hydroxide ◽  
Crystallite Size ◽  
Narrow Range ◽  
Crystallinity Index ◽  
Cellulose Ii ◽  
Cellulose I ◽  
Native Cellulose ◽  
Wide Range ◽  
Different Sources ◽  
Low Crystallinity

Native cellulose samples having a wide range of crystallinity and crystallite size were mercerized by treatment with sodium hydroxide. The resultant cellulose II samples showed only a narrow range of crystallinity and an essentially constant crystallite size. For the low-crystallinity samples, crystallinity and crystallite size actually increased on mercerization. These results are in line with the proposal that mercerization involves the mingling of chains from adjacent and antiparallel cellulose I microfibrils to form cellulose II crystals of antiparallel chains.

Structure of Cellulose Isolated from Rapeseed (Brassica Napus L.) Stalks

2019 ◽  
Author(s):  
Bogdan-Marian Tofanica ◽  
Emanuela Callone
Keyword(s):  
Brassica Napus ◽  
Cellulose Ii ◽  
Cellulose I ◽  
Brassica Napus L ◽  
Crystalline Structures ◽  
Native Cellulose ◽  
First Time

We characterized for the first time the rapeseed stalk’s cellulose and it has been found that native cellulose occurs as Cellulose I allomorph, while α-cellulose consists of particular crystalline structures as seen in cellulose II.

Synergistic Effect of Mixed Bases in the Conversion of Cotton Cellulose I to Cellulose II

1969 ◽  
Vol 39 (4) ◽  
pp. 305-316 ◽  
Author(s):  
Tyrone L. Vigo ◽  
Ricardo H. Wade ◽  
Donald Mitcham ◽  
Clark M. Welch
Keyword(s):  
Synergistic Effect ◽  
Sodium Hydroxide ◽  
Lithium Hydroxide ◽  
Cellulose Ii ◽  
Organic Base ◽  
X Ray Diffraction ◽  
Cellulose I ◽  
Quaternary Base ◽  
Cation Size ◽  
High Degree

Several aqueous bases were found which swell cotton yarn greatly, but, after their removal from the cotton, leave the x-ray diffraction pattern unchanged from that of native cellulose I. Such bases include 9.5% lithium hydroxide and 35% benzyltrimethylammonium hydroxide. However, the addition of as little as 1.5% lithium hydroxide or 5% sodium hydroxide, to the benzyltrimethylammonium hydroxide causes substantial conversion of cellulose I to cellulose II. This synergistic effect is attributed to the decrystallizing action of the organic base which, by breaking down the cellulose I lattice, facilitates the action of lithium, sodium, and potassium hydroxides in forming alkali cellulose lattices leading to cellulose II. Rubidium and cesium hydroxides failed to produce this effect when added to the organic base. Cellulose swelling, decrystallization, and recrystallization appear to be distinct steps in lattice conversion. These steps may present greatly different requirements as to optimum cation size and coordination, such requirements being more readily met by mixtures of cations than by any one species. In the absence of the quaternary base, but at alkali concentrations giving maximum fiber swelling, no lattice conversion was produced by lithium or cesium hydroxides, a high degree of conversion occurred with sodium hydroxide, and the other alkalies were intermediate in effect. The strength, elongation, energy-to-rupture, and tenacity of treated yarns varied greatly with the cations present in the alkali. In contrast to yarn, fiber bundles underwent slow and partial conversion to cellulose II by the quaternary base.

Structure of Cellulose Isolated from Rapeseed (Brassica Napus L.) Stalks

2019 ◽  
Author(s):  
Bogdan-Marian Tofanica ◽  
Emanuela Callone
Keyword(s):  
Brassica Napus ◽  
Cellulose Ii ◽  
Cellulose I ◽  
Brassica Napus L ◽  
Crystalline Structures ◽  
Native Cellulose ◽  
First Time

We characterized for the first time the rapeseed stalk’s cellulose and it has been found that native cellulose occurs as Cellulose I allomorph, while α-cellulose consists of particular crystalline structures as seen in cellulose II.

scholarly journals Extraction and Characterization of Cellulose Nanowhiskers  from TEMPO Oxidized Sisal Fibers

2021 ◽  
Author(s):  
FANGWEI FAN ◽  
MENGTING ZHU ◽  
KAIYANG FANG ◽  
ENDI CAO ◽  
YINZHI YANG ◽  
...  
Keyword(s):  
Sodium Hydroxide ◽  
Sisal Fiber ◽  
Cellulose Ii ◽  
Cellulose Nanowhiskers ◽  
Cellulose I ◽  
Alkali Pretreatment ◽  
Sodium Hydroxide Concentration ◽  
Carboxylate Groups ◽  
Sisal Fibers

Abstract Cellulose nanowhiskers as one kind of renewable and biocompatible nanomaterials evoke much interest because of its versatility in various applications. Herein, the sisal cellulose nanowhiskers with length of 100–500 nm, ultrathin diameter of 6–61 nm, high crystallinity of 74.74 % and C6 carboxylate groups converted from C6 primary hydroxyls were prepared via a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)/NaBr/NaClO system selective oxidization combined with mechanical homogenization. The effects of sodium hydroxide concentration in alkali pretreatment on the final sisal cellulose nanowhiskers were explored. It was found that with the increase of sodium hydroxide concentration, the sisal fiber crystalline type would change from cellulose I to cellulose II. The versatile sisal cellulose nanowhiskers would be particularly useful for applications in the nanocomposites as reinforcing phase, as well as in tissue engineering, filtration, pharmaceutical and optical industries as additives.

scholarly journals Changes in the Dimensions of Lignocellulose Nanofibrils with Different Lignin Contents by Enzymatic Hydrolysis

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2201
Author(s):  
Jae-Hyuk Jang ◽  
Noriko Hayashi ◽  
Song-Yi Han ◽  
Chan-Woo Park ◽  
Fauzi Febrianto ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Lignin Content ◽  
Crystallinity Index ◽  
Average Diameter ◽  
Cellulose I ◽  
Composition And Structure ◽  
Wide Range ◽  
Acetic Acid Treatment ◽  
Disk Mill ◽  
Lignocellulose Nanofibrils

Changes in the dimensions of lignocellulose nanofibrils (LCNFs) with different lignin contents from betung bamboo (Dendrocalamus asper) by enzymatic hydrolysis using endoglucanase (EG) were investigated. Lignin contents were adjusted from 3% to 27% by NaClO2/acetic acid treatment, and LCNFs were prepared using a wet disk-mill (WDM). The dimensions of the LCNFs significantly decreased with decreasing lignin content and increasing EG addition. With increasing EG content, the average diameter of the LCNFs significantly decreased, even though they contained parts of hemicellulose and lignin. The crystal structure showed the typical cellulose I structure in all samples, but the intensity of the diffraction peak slightly changed depending on the lignin and EG contents. The crystallinity index (CrI) values of the LCNFs increased a maximum of 23.8% (LCNF-L27) under increasing EG addition, regardless of the lignin content. With the EG addition of three times the LCNF amount, LCNF-L3 showed the highest CrI value (59.1%). By controlling the composition and structure of LCNFs, it is expected that the wide range of properties of these materials can extend the property range available for existing materials.

scholarly journals Microstructure, Hardness, and Elastic Modulus of a Multibeam-Sputtered Nanocrystalline Co-Cr-Fe-Ni Compositional Complex Alloy Film

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3357
Author(s):  
Péter Nagy ◽  
Nadia Rohbeck ◽  
Zoltán Hegedűs ◽  
Johann Michler ◽  
László Pethö ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Crystallite Size ◽  
Physical Vapor Deposition ◽  
Defect Density ◽  
Lattice Defect ◽  
Chemical Compositions ◽  
Line Profile Analysis ◽  
Face Centered Cubic ◽  
Complex Alloy ◽  
Wide Range

A nanocrystalline Co-Cr-Ni-Fe compositional complex alloy (CCA) film with a thickness of about 1 micron was produced by a multiple-beam-sputtering physical vapor deposition (PVD) technique. The main advantage of this novel method is that it does not require alloy targets, but rather uses commercially pure metal sources. Another benefit of the application of this technique is that it produces compositional gradient samples on a disk surface with a wide range of elemental concentrations, enabling combinatorial analysis of CCA films. In this study, the variation of the phase composition, the microstructure (crystallite size and defect density), and the mechanical performance (hardness and elastic modulus) as a function of the chemical composition was studied in a combinatorial Co-Cr-Ni-Fe thin film sample that was produced on a surface of a disk with a diameter of about 10 cm. The spatial variation of the crystallite size and the density of lattice defects (e.g., dislocations and twin faults) were investigated by X-ray diffraction line profile analysis performed on the patterns taken by synchrotron radiation. The hardness and the elastic modulus were measured by the nanoindentation technique. It was found that a single-phase face-centered cubic (fcc) structure was formed for a wide range of chemical compositions. The microstructure was nanocrystalline with a crystallite size of 10–27 nm and contained a high lattice defect density. The hardness and the elastic modulus values measured for very different compositions were in the ranges of 8.4–11.8 and 182–239 GPa, respectively.

scholarly journals Subject-specific multiscale modeling of aortic valve biomechanics

2021 ◽  
Author(s):  
G. Rossini ◽  
A. Caimi ◽  
A. Redaelli ◽  
E. Votta
Keyword(s):  
Aortic Valve ◽  
Boundary Conditions ◽  
Narrow Range ◽  
Radial Strain ◽  
Length Scale ◽  
Length Scales ◽  
Anatomical Features ◽  
Wide Range ◽  
Subject Specific ◽  
Cell Strains

AbstractA Finite Element workflow for the multiscale analysis of the aortic valve biomechanics was developed and applied to three physiological anatomies with the aim of describing the aortic valve interstitial cells biomechanical milieu in physiological conditions, capturing the effect of subject-specific and leaflet-specific anatomical features from the organ down to the cell scale. A mixed approach was used to transfer organ-scale information down to the cell-scale. Displacement data from the organ model were used to impose kinematic boundary conditions to the tissue model, while stress data from the latter were used to impose loading boundary conditions to the cell level. Peak of radial leaflet strains was correlated with leaflet extent variability at the organ scale, while circumferential leaflet strains varied over a narrow range of values regardless of leaflet extent. The dependency of leaflet biomechanics on the leaflet-specific anatomy observed at the organ length-scale is reflected, and to some extent emphasized, into the results obtained at the lower length-scales. At the tissue length-scale, the peak diastolic circumferential and radial stresses computed in the fibrosa correlated with the leaflet surface area. At the cell length-scale, the difference between the strains in two main directions, and between the respective relationships with the specific leaflet anatomy, was even more evident; cell strains in the radial direction varied over a relatively wide range ($$0.36-0.87$$ 0.36 - 0.87 ) with a strong correlation with the organ length-scale radial strain ($$R^{2}= 0.95$$ R 2 = 0.95 ); conversely, circumferential cell strains spanned a very narrow range ($$0.75-0.88$$ 0.75 - 0.88 ) showing no correlation with the circumferential strain at the organ level ($$R^{2}= 0.02$$ R 2 = 0.02 ). Within the proposed simulation framework, being able to account for the actual anatomical features of the aortic valve leaflets allowed to gain insight into their effect on the structural mechanics of the leaflets at all length-scales, down to the cell scale.

Research of the Chlorine Sorption Processes when its Deposition by Water Aerosol

2021 ◽  
Vol 1038 ◽  
pp. 361-373
Author(s):  
Maksym Kustov ◽  
Andriy Melnychenko ◽  
Dmytro Taraduda ◽  
Alla Korogodska
Keyword(s):  
Sodium Hydroxide ◽  
Water Flow ◽  
Experimental Verification ◽  
Sorption Process ◽  
Water Aerosol ◽  
Sorption Model ◽  
Laboratory Facility ◽  
Wide Range ◽  
Hazardous Gases ◽  
Experimental Laboratory

Modified stepwise model of gas sorption process with finely dispersed water flow. The sorption model allows forecasting the intensity of hazardous gases deposition with adequate for the emergency recovery conditions accuracy using minimum input parameters. This allows using the sorption model under the conditions of emergency and increasing the forecasting promptness. Use of chemical neutralizer is proposed to increase the effectiveness of chlorine hazardous gas deposition. Use of sodium hydroxide is proposed as the chlorine chemical neutralizer, which is easily dissolved in water, non-toxic and easy to store. An experimental laboratory facility was developed and created with the purpose of experimental verification of the sorption processes, which allows researching the sorption processes by liquid aerosols within a wide range of dispersity. Adequacy of the existing models as well as the modified one was verified experimentally. The verification results showed a 5% indicator of the theoretical and experimental results compliance.

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