Influence of Aging Time on the Structural Changes of Cassava Thermoplastic Starch

2012 ◽  
Vol 1372 ◽  
Author(s):  
José H. Mina ◽  
Alex Valadez ◽  
Pedro J. Herrera-Franco ◽  
Tanit Toledano
Keyword(s):  
Yield Stress ◽  
Amorphous Phase ◽  
Structural Changes ◽  
Thermoplastic Starch ◽  
X Ray Diffraction ◽  
X Ray ◽  
Second Stage ◽  
Diffraction Patterns ◽  
Type V ◽  
Stress Drops

ABSTRACTIn this work the change in the structural properties of cassava (manihot sculenta Crantz) thermoplastic starch (TPS) under controlled environment (humidity and temperature) was studied. Fourier Transform Infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results showed an evident increasing in the amorphous phase of the TPS regarding the native starch. There was a relative decrease of the band at 1047 cm-1 associated to crystalline structure of starch compared to the amorphous peak at 1022 cm-1. The X-ray diffraction patterns confirmed the increment of the amorphous phase in the TPS samples. Likewise the X-ray diffraction patterns shows evidence of residual type C crystallinity and the formation of a new crystalline phase type VH due to the orientation induced in plasticization process. In first stage of conditioning the tensile yield stress drops from 7.5 drops to 0.5 MPa and the break strain increases 1000%. At the same time it seems that the crystallinity of the samples increases as was evidenced by the gradually increasing of the FTIR band at 1047 cm-1. In a second stage, the yield stress increases, the break strain drops and the crystallinity continue growing steadily. These findings suggest that coexist two phenomena simultaneously in the samples. A phenomenon of re-crystallization (retrogradation) that tends to make the material more stiff and a process of plasticization that tends to softening it. It seems that the latter mechanism predominates in the first stage, at short times, and the former in the second stage, at older times.

scholarly journals Preparation and Properties of Nanocellulose from Miscanthus x giganteus

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Valerii A. Barbash ◽  
Olha V. Yashchenko ◽  
Olesia A. Vasylieva
Keyword(s):  
Structural Changes ◽  
Thermochemical Treatment ◽  
Crystallinity Index ◽  
Alkaline Treatment ◽  
X Ray Diffraction ◽  
Miscanthus X Giganteus ◽  
X Ray ◽  
Second Stage ◽  
20 Nm ◽  
Hydrolysis Of

Miscanthus x giganteus stalks were used to make organosolvent pulp and nanocellulose. The organosolvent miscanthus pulp (OMP) was obtained through thermal treatment in the mixture of glacial acetic acid and hydrogen peroxide at the first stage and the alkaline treatment at the second stage. Hydrolysis of the never-dried OМP was carried out by a solution of sulfuric acid with concentrations of 43% and 50% and followed by ultrasound treatment. Structural changes and the crystallinity index of OMP and nanocellulose were studied by SEM and FTIR methods. X-ray diffraction analysis confirmed an increase in the crystallinity of OMP and nanocellulose as a result of thermochemical treatment. We show that nanocellulose has a density of up to 1.6 g/cm3, transparency up to 82%, and a crystallinity index of 76.5%. The AFM method showed that the particles of nanocellulose have a diameter in the range from 10 to 20 nm. A thermogravimetric analysis confirmed that nanocellulose films have a denser structure and lower mass loss in the temperature range of 320–440°C compared to OMP. The obtained nanocellulose films have high tensile strength up to 195 MPa. The nanocellulose obtained from OMP exhibits the improved properties for the preparation of new nanocomposite materials.

Ferromagnetic properties and Nanocrystallization behavior of Amorphous (Fe0.99Mo0.01)78Si9B13 Ribbons

2001 ◽  
Vol 674 ◽  
Author(s):  
Xiang-Cheng Sun ◽  
J. A. Toledo ◽  
S. Galindo ◽  
W. S. Sun
Keyword(s):  
Amorphous Phase ◽  
Magnetic Ordering ◽  
Metastable Phases ◽  
X Ray Diffraction ◽  
Ferromagnetic Properties ◽  
X Ray ◽  
Diffraction Patterns ◽  
Optimum Annealing Temperature ◽  
Increasing Temperature ◽  
Differential Scanning Calorimeters

ABSTRACTFerromagnetic properties and nanocrystallization process of soft ferromagnetic (Fe0.99Mo0.01)78Si9B13 ribbons are studied by transmission electron microscope (TEM), X-ray diffraction (XRD), Mössbauer spectroscopy (MS), differential scanning calorimeters (DSC) and magnetization measurements. The Curie and crystallization temperature are determined to be TC=665K and Tx = 750K, respectively. The Tx value is in well agreement with DSC measurement results. X-ray diffraction patterns had shown a good reconfirm of two metastable phases (Fe23B6, Fe3B) were formed under in-situ nanocrystallization process. Of which these metastable phases embedded in the amorphous matrix have a significant effect on magnetic ordering. The ultimate nanocrystalline phases of α-Fe (Mo, Si) and Fe2B at optimum annealing temperature had been observed respectively. It is notable that the magnetization of the amorphous phase decreases more rapidly with increasing temperature than those of nanocrystalline ferromagnetism, suggesting the presence of the distribution of exchange interaction in the amorphous phase or high metalloid contents.

Rapid small-angle X-ray diffraction of a tonically contracting molluscan smooth muscle recorded with imaging plates

1989 ◽  
Vol 22 (1) ◽  
pp. 72-74 ◽  
Author(s):  
Y. Tajima ◽  
K. Okada ◽  
O. Yoshida ◽  
T. Seto ◽  
Y. Amemiya
Keyword(s):  
Small Angle ◽  
Structural Changes ◽  
High Sensitivity ◽  
Imaging Plate ◽  
Layer Line ◽  
X Ray Diffraction ◽  
Thin Filaments ◽  
X Ray ◽  
Area Detector ◽  
Diffraction Patterns

Small-angle X-ray diffraction patterns from the anterior byssus retractor muscles of Mytilus edulis contracting tonically in response to stimulation with acetylcholine were recorded in a 30 s exposure with synchrotron radiation and a high-sensitivity X-ray area detector called an imaging plate. The 190 Å layer line from the thin filaments increased in intensity with increase in tonic tension up to 6 x 104 kg m−2. Above this value, the layer-line intensity remained almost constant and comparable to that for a contracting skeletal muscle, indicating that the same structural changes of the thin filaments occur in both muscles.

scholarly journals The growth of decagonal Al–Co–Ni single crystals as a function of chemical composition

1997 ◽  
Vol 12 (9) ◽  
pp. 2274-2280 ◽  
Author(s):  
B. Zhang ◽  
M. Estermann ◽  
W. Steurer
Keyword(s):  
Single Crystals ◽  
Structural Changes ◽  
Ternary Systems ◽  
X Ray Diffraction ◽  
X Ray ◽  
Decagonal Phase ◽  
Different Types ◽  
Diffraction Patterns ◽  
The Stability ◽  
Diagram Analysis

Decaprismatic single crystals taken from a series of alloys of nominal compositions within Al65–77Co3–22Ni3–22 have been studied by means of x-ray diffraction techniques. The substitution of Co by Ni in increasing amounts changes the (pseudo)decagonal diffraction patterns drastically and indicates structural changes which range from a single-crystalline approximant via orientationally ordered nanodomain structures and quasiperiodic phases with different types of ordering phenomena, to a basic decagonal phase. A quantum phase diagram analysis shows a clear separation of the stability regions of the ternary systems described in this study and other decagonal phases.

Photoinduced structural dynamics of polar solids studied by femtosecond X-ray diffraction

2010 ◽  
Vol 66 (2) ◽  
pp. 168-178 ◽  
Author(s):  
Thomas Elsaesser ◽  
Michael Woerner
Keyword(s):  
Real Time ◽  
Structural Changes ◽  
Bragg Diffraction ◽  
X Ray Diffraction ◽  
Crystalline Materials ◽  
X Ray ◽  
Density Maps ◽  
Diffraction Patterns ◽  
Superlattice Structures ◽  
Work Done

Femtosecond X-ray diffraction allows for real-time mapping of structural changes in condensed matter on atomic length and timescales. Sequences of diffraction patterns provide both transient geometries and charge-density maps of crystalline materials. This article reviews recent progress in this field, the main emphasis being on experimental work done with laser-driven hard X-ray sources. Both Bragg diffraction techniques for bulk and nanostructured single crystals as well as the recently implemented powder diffraction from polycrystalline samples are discussed. In ferroelectric superlattice structures, coherent phonon motions and the driving stress mechanisms are observed in real time. In molecular crystals charge-transfer processes and the concomitant changes of the lattice geometry are analyzed.

Some Low-Angle X-Ray Evidence on the Structural Changes in Thermally- and Plasma-Treated Wool

1976 ◽  
Vol 46 (11) ◽  
pp. 779-785 ◽  
Author(s):  
Kay Sue Lee
Keyword(s):  
Diffraction Pattern ◽  
Structural Changes ◽  
Azimuthal Angle ◽  
Prolonged Treatment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Resistant ◽  
Diffraction Patterns ◽  
Meridional Reflection ◽  
Thermally Treated

A series of events occurred when wool was heated in vacuum. At some stages structural changes in the thermally-treated wool were observed, as reflected in the low-angle x-ray diffraction patterns. An increase in the intensity of the 39 Å meridional reflection and the appearance of a 4-point diagram with azimuthal angle of 45° at about 46 Å spacing were observed when wool was heated near 170°C for 90 min. Similar results were found in samples heated at higher temperatures but for shorter time. The most heat-resistant meridional reflection is the 66 Å. The low-angle x-ray diffraction patterns of plasma-treated wool showed only disappearance of the sharp lipid ring at 48 Å. No intensification of any reflection was observed. Prolonged treatment with plasma destroys the low-angle x-ray diffraction pattern of wool.

Two-dimensional Wide-Angle X-ray Scattering on a Cm-doped borosilicate glass in a beryllium container

2021 ◽  
Vol 28 (1) ◽  
pp. 214-223
Author(s):  
Olivier Bouty ◽  
Laure Ramond ◽  
Kathy Dardenne ◽  
Jörg Rothe
Keyword(s):  
Borosilicate Glass ◽  
Structural Changes ◽  
Glass Network ◽  
High Energy ◽  
Wide Angle ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Diffraction Patterns

The two-dimensional wide-angle X-ray diffraction technique was applied to a Cm-doped borosilicate glass in a beryllium container. The experiment involved a high-energy X-ray beam and an image plate. It is shown that it is possible to extract the structure factor of the radioactive glass successfully from diffraction patterns and compare it with that of the pristine one. Striking differences appear under the first diffraction peak, revealing new sub-structures for the radioactive glass. It is suggested that they could be related to structural changes in the medium-range order, in particular the size distribution of rings or chains under the influence of mixed interactions between the glass network, α-particles and recoil nuclei.

scholarly journals X-Ray Study of Interfacial Interactions in Highly Milled Sn-Ge Powders

1991 ◽  
Vol 238 ◽  
Author(s):  
J.K.D.S. Jayanetti ◽  
S. M. Heald ◽  
Z. Tan
Keyword(s):  
Melting Point ◽  
Amorphous Phase ◽  
Room Temperature ◽  
Structural Changes ◽  
X Ray Diffraction ◽  
Interfacial Interactions ◽  
X Ray ◽  
Milled Powders

ABSTRACTWe have studied possible structural changes occur ing at the Sn/Ge interface of highly milled Sn/Ge composites. EXAFS and X-ray Diffraction measurements were made on mechanically milled powders having compositions ranging from 20 to SO vol.% Sn. X-ray diffraction measurements indicate the increasing amorphization of Sn as the Sn content is decreased. EXAFS results indicate that this amorphous phase is due to the formation of an a-Sn/Ge alloy. The EXAFS from this alloy did not change significantly at the Sn melting point. X-ray diffraction measurements made at room temperature show a systematic decrease in the intensity of Sn peaks and broadening of Ge peaks with the decreasing Sn content.

Radiation Induced Structural Changes in Normal Spinels

2007 ◽  
Vol 1043 ◽  
Author(s):  
David Simeone ◽  
Gianguido Baldinozzi ◽  
Dominique Gosset ◽  
Leo Mazerolles ◽  
Lionel Thome
Keyword(s):  
Radiation Effects ◽  
Structural Changes ◽  
Ion Irradiation ◽  
Atomic Scale ◽  
X Ray Diffraction ◽  
Unified Framework ◽  
X Ray ◽  
Transmission Electron ◽  
Radiation Induced ◽  
Diffraction Patterns

AbstractIon irradiation induced phase transformations in three normal spinel compounds MgAl2O4, MgCr2O4 and ZnAl2O4 have been investigated by X-ray diffraction, Raman spectroscopy and Transmission Electron Microscopy. This work presents a unified framework to describe the radiation effects in normal spinels. Irradiation modifies the atomic and mesoscopic structures of theses spinels in different ways. At the atomic scale, it produces the inversion of the cations in the spinel structure which can always be described within its usual Fd-3m space group. At the mesoscopic scale, it produces microdomains, responsible for the important changes in the X-ray diffraction patterns.

Low-Temperature X-Ray Diffraction of Frozen Electrolytes

1961 ◽  
Vol 5 ◽  
pp. 48-56 ◽  
Author(s):  
H.J. Weltman
Keyword(s):  
Low Temperature ◽  
Room Temperature ◽  
Structural Changes ◽  
Polycrystalline Material ◽  
Sample Introduction ◽  
X Ray Diffraction ◽  
Strip Chart Recorder ◽  
X Ray ◽  
Chart Recorder ◽  
Diffraction Patterns

AbstractA low-temperature X-ray diffraction apparatus has been constructed to study structure and structural changes of electrolytes in the frozen state. This apparatus, which is inexpensive and easy to construct, is an attachment to a standard wide-angle diffractometer. Diffraction patterns may be obtained of various types of materials at any temperature from room temperature to −196°C with a control of ±1°C. The diffraction patterns are recorded on a strip-chart recorder as they are being obtained. Thus, this diffractometer method has several advantages over the camera methods usually employed for low-temperature X-ray diffraction work. A unique sample-introduction method is described which ensures a polycrystalline material suitable for obtaining diffraction patterns. Such patterns are shown for various concentrations of salts in water at several low temperatures, phase transformations being in evidence.

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