X-ray Diffraction: An Efficient Method to Determine Microfibrillar Angle of Dry and Matured Cellulosic Fibers.

2020 ◽  
pp. 1-8
Author(s):  
B. Rekha ◽  
B. NagarajaGanesh
Keyword(s):  
Efficient Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cellulosic Fibers ◽  
Microfibrillar Angle

An Evaluation of Some Profile Models and the Optimization Procedures Used in Profile Fitting

1982 ◽  
Vol 26 ◽  
pp. 73-80 ◽  
Author(s):  
Scott A. Howard ◽  
Robert L. Snyder
Keyword(s):  
Least Squares ◽  
Efficient Method ◽  
Optimization Algorithm ◽  
Optimization Technique ◽  
Silicon Sample ◽  
X Ray Diffraction ◽  
Profile Function ◽  
X Ray ◽  
Profile Fitting ◽  
Time Required

AbstractThis paper examines some of the concerns regarding the development of an algorithm for the refinement of X-ray diffraction profiles. The object of the algorithm is to provide a time efficient method of refinement through the choice of a suitable profile function and optimization technique.Seven profile models were tested using a least-squares error criterion for refinement. Profile parameters were refined using non-linear Gauss-Newton, Marquardt and Simplex algorithms. The profiles were refined on a pattern digitally collected from an NBS 640A silicon sample.The results of this study indicate the repetitive function evaluations are not necessarily the time consuming step in the profile fitting process. As the number of parameters needed to evaluate the profile and the number of points in the profile increases, the time required to perform the mathematics in the Gauss-Newton and Marquardt algorithms increases. Although the Simplex was most memory and time efficient, our Gauss-Newton optimization algorithm provided a more consistent set of refined values which were not as dependent on the initial estimates of the parameters.The most favorable results were obtained by using the split Pearson VII profile with the alpha 2 reflection fixed in position and intensity with respect to the alpha 1 reflsction. This method generated the lowest residual error and was found to avoid some problems resulting from the alpha 1, alpha 2 line overlap.

scholarly journals Insight into the Evolution of the Cellulose Microstructure Through the Enzyme Pretreatment Method

2021 ◽  
Author(s):  
Qijun Ding ◽  
Limin Jing ◽  
Wenjia Han ◽  
Yanpeng Guan ◽  
Yifei Jiang ◽  
...  
Keyword(s):  
Degree Of Polymerization ◽  
Correlation Spectroscopy ◽  
X Ray Diffraction ◽  
Pretreatment Method ◽  
X Ray ◽  
Cellulosic Fibers ◽  
Enzyme Pretreatment ◽  
Theoretical Support ◽  
Derivative Analysis ◽  
Insight Into

Abstract In this work, the changes of properties and microstructure of cellulose (bleached hardwood kraft pulp (BHKP)) subjected to different enzyme pretreatment times (0–10 h) were explored for further fibrillation. The various properties of the pretreated cellulose gradually decrease with the elapse of time relative to the pristine material, such as yield, water retention value, aspect ratio and degree of polymerization, etc. Enzyme pretreatment can promote the peeling of fibrils and loosen the amorphous areas of cellulose identified by Scanning Electron Microscope (SEM) and X-ray diffraction (XRD). A thorough investigation of the relation between pretreatment and evolution of inter-/intra-molecular H-bonds in cellulose was conducted including content and cleave sequence of H-bonds by Fourier transform infrared spectroscopy (FTIR), second derivative analysis and generalized two-dimensional correlation spectroscopy (2DCOS). The intermolecular H-bonds with the most significant decrease in content was cleaved first relative to the intramolecular H-bonds. These discoveries provide theoretical support to more effective pretreatment method for commercial production of fibrils from cellulosic fibers.

The combined effects of initial microfibrillar angle and moisture contents on the tensile mechanical properties and angle alteration of wood foils during tension

Holzforschung ◽  
2017 ◽  
Vol 71 (6) ◽  
pp. 491-497 ◽  
Author(s):  
Hankun Wang ◽  
Zixuan Yu ◽  
Xuexia Zhang ◽  
Dan Ren ◽  
Yan Yu
Keyword(s):  
Tensile Properties ◽  
Microfibril Angle ◽  
Tensile Modulus ◽  
Pinus Massoniana ◽  
Combined Effects ◽  
X Ray Diffraction ◽  
Masson Pine ◽  
X Ray ◽  
Microfibrillar Angle

Abstract The combined effects of initial microfibril angle (MFA) and moisture content (MC) on the longitudinal tensile properties of Masson pine (Pinus massoniana Lamb.) wood foils has been investigated. Synchrotron X-ray diffraction (XRDsyn) combined with a custom-built microtensile device was applied for in situ monitoring of the MFA alterations in the foils under different initial MFAs and MCs conditions. The results demonstrate that the tensile properties are highly negatively correlated to both MFA and MC. Furthermore, the tensile modulus is more sensitive to MC change than tensile strength. At a higher MFA, the sensitivity of the two mechanical indicators to MC alteration is enhanced.

scholarly journals Characterization of novel natural fiber from manau rattan (Calamus manan) as a potential reinforcement for polymer-based composites

2021 ◽  
Author(s):  
Linhu Ding ◽  
Xiaoshuai Han ◽  
Huiling Li ◽  
Jingquan Han ◽  
Lihua Cao ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Natural Fiber ◽  
Natural Fibers ◽  
Morphological Properties ◽  
Thermoplastic Composites ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Cellulosic Fibers ◽  
Degradation Temperature

Abstract The study on novel natural fibers in polymer-based composites will help promote the invention of novel reinforcement and expand their possible applications. Herein, novel cellulosic fibers were extracted from the stem of manau rattan (Calamus manan) by mechanical separation. It is the first time to comprehensively analyze and study the chemical, thermal, mechanical and morphological properties of manau rattan fibers by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction Analysis (XRD), Thermogravimetric Analysis (TGA), single fiber tensile test and Scanning Electron Microscopy (SEM). Component analysis results showed the cellulose, hemicellulose and lignin contents of manau rattan fibers were 42, 20, and 27%, respectively. The surface of the rattan fiber was hydrophilic according to the oxygen/carbon ratio of 0.49. Manau rattan has a high crystalline index of 48.28%, inducing a high maximum degradation temperature of 332.8°C. This reveals that it can be used as a reinforcement for thermoplastic composites whose operating temperature is below 300°C. The average tensile strength can reach 273.28 MPa, which is beneficial to improve the mechanical properties of rattan fiber reinforced composites. SEM images displayed the rough surface of the fiber, which helps to enhance the interfacial adhesion between the fibers and matrices in composites. This work was also in comparison with some other natural fibers. The above analysis and research showed the great potential of manau rattan fibers as the reinforcement in polymer-based composites.

scholarly journals Biocomposite Fabrication from Enzymatically Treated Nanocellulosic Fibers and Recycled Polylactic Acid

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1003 ◽  
Author(s):  
Mohamed Amine Laadila ◽  
Gayatri Suresh ◽  
Tarek Rouissi ◽  
Pratik Kumar ◽  
Satinder Kaur Brar ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Tensile Stress ◽  
Polylactic Acid ◽  
Break Point ◽  
X Ray Diffraction ◽  
Hemp Fibers ◽  
X Ray ◽  
Cellulosic Fibers ◽  
Significant Difference ◽  
Scanning Electron

Recycled polylactic acid (PLAr) was reinforced with treated nanocellulosic hemp fibers for biocomposite fabrication. Cellulosic fibers were extracted from hemp fibers chemically and treated enzymatically. Treated nanocellulosic fibers (NCF) were analyzed by Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Biocomposite fabrication was done with PLAr and three concentrations of treated NCF (0.1%, 0.25%, and 1% (v/v)) and then studied for thermal stability and mechanical properties. Increased thermal stability was observed with increasing NCF concentrations. The highest value for Young’s modulus was for PLAr + 0.25% (v/v) NCF (250.28 ± 5.47 MPa), which was significantly increased compared to PLAr (p = 0.022). There was a significant decrease in the tensile stress at break point for PLAr + 0.25% (v/v) NCF and PLAr + 1% (v/v) NCF as compared to control (p = 0.006 and 0.002, respectively). No significant difference was observed between treatments for tensile stress at yield.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

Electron Microscopy of Human Gallstones

1971 ◽  
Vol 29 ◽  
pp. 296-297
Author(s):  
C. Wolpers ◽  
R. Blaschke
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Bile Pigment ◽  
X Ray Diffraction ◽  
Triclinic Crystal System ◽  
X Ray ◽  
Follow Up Study ◽  
Infra Red ◽  
Main Components

Scanning microscopy was used to study the surface of human gallstones and the surface of fractures. The specimens were obtained by operation, washed with water, dried at room temperature and shadowcasted with carbon and aluminum. Most of the specimens belong to patients from a series of X-ray follow-up study, examined during the last twenty years. So it was possible to evaluate approximately the age of these gallstones and to get information on the intensity of growing and solving.Cholesterol, a group of bile pigment substances and different salts of calcium, are the main components of human gallstones. By X-ray diffraction technique, infra-red spectroscopy and by chemical analysis it was demonstrated that all three components can be found in any gallstone. In the presence of water cholesterol crystallizes in pane-like plates of the triclinic crystal system.

High Resolution Replication of Organoclay Surfaces

1982 ◽  
Vol 40 ◽  
pp. 576-577
Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys
Keyword(s):  
Clay Mineral ◽  
Organic Molecule ◽  
Organic Molecules ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Naturally Occurring ◽  
Silicate Layers ◽  
Mineral Identification

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.

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