Crystallization in Unstretched Rubber. Microscopic Study in Polarized Light

1951 ◽  
Vol 24 (3) ◽  
pp. 550-556
Author(s):  
H. N. Campbell ◽  
M. D. Allen
Keyword(s):  
Low Temperature ◽  
Physical Properties ◽  
Melting Temperature ◽  
Microscopic Study ◽  
Room Temperature ◽  
Polarized Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Limited Mobility ◽  
Sensitive Method

Abstract Since many elastomers indicate by their physical properties that crystallization occurs even when such crystallization is not detectable by x-ray diffraction, a direct microscopic study in polarized light was undertaken. This study confirms the presence of such crystallinity not only in rubber but also in polybutadiene and some low-temperature copolymers. Furthermore, the same crystal pattern is reproduced on melting and refreezing provided the intermediate melting temperature is not too high. This indicates that x-ray diffraction is not a very sensitive method for detecting small amounts of crystallinity in high polymers. The reproduction of the crystal pattern on refreezing shows that the molecular segments have limited mobility even at room temperature; this may require revision of current theories of the origin of retractive forces in elastomers.

Low-temperature crystal structure of RS-thiocamphor

2004 ◽  
Vol 219 (9) ◽  
Author(s):  
E. Louise R. Robins ◽  
Michela Brunelli ◽  
Asiloé J. Mora ◽  
Andrew N. Fitch
Keyword(s):  
Crystal Structure ◽  
Phase Transitions ◽  
Low Temperature ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Two Phase ◽  
X Ray ◽  
Low Temperature Crystal Structure

AbstractDSC and high-resolution powder X-ray diffraction measurements in the range 295 K–100 K show that RS-thiocamphor undergoes two phase transitions. The first, at around 260 K on cooling, is from the room-temperature body-centred-cubic phase to a short-lived intermediate. At 258 K the low-temperature form starts to appear. The crystal structure of the latter is orthorhombic, space group

scholarly journals The Effect of Thickness on the Physical Properties of Fe2O3 Thin Films Prepared by DC Magnetron Sputtering

2017 ◽  
Vol 28 (1) ◽  
pp. 149
Author(s):  
Baha'a A. Al-Hilli
Keyword(s):  
Film Thickness ◽  
Physical Properties ◽  
Room Temperature ◽  
Optical Constants ◽  
Energy Gap ◽  
Nano Particle ◽  
X Ray Diffraction ◽  
Thin Film Thickness ◽  
X Ray ◽  
Deposition Parameters

The objective of this study is to assess the influence of nano-particle Fe2O3 thin film thickness on some physical properties which were prepared by magnetron DC- sputtering on glass substrate at room temperature. The structure was tested with X-Ray diffraction and it was to be amorphous and to become single crystal with recognized peak in (003) after annealing at temperature 500oC. The physical properties as a function of deposition parameters and then film thickness were studied. The optical properties such as absorbance, energy gap and some optical constants are measured and found that of about (3eV) energy gap.

Heterogeneous Strain Relaxation in GaAs on Si (100)

1988 ◽  
Vol 116 ◽  
Author(s):  
A. Freundlich ◽  
G. Neu ◽  
A. Leycuras ◽  
R. Carles ◽  
C. Verie
Keyword(s):  
Residual Stress ◽  
Low Temperature ◽  
Room Temperature ◽  
Strain Relaxation ◽  
Photoluminescence Excitation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Si Substrates ◽  
Low Temperature Photoluminescence ◽  
Epilayer Surface

AbstractResidual stress in MOVPE grown GaAs on (100)Si substrates is investigated using Haman spectroscopy, X-ray diffraction, low temperature photoluminescence and photoluminescence excitation spectroscopy experiments. At room temperature, 2 µm-thick GaAs/Si is found to be under biaxial (100) tensile stress of X = 1.8 ± 0.3 kbar, near the epilayer surface. The stress magnitude decreases as the distance from interface decreases. PL and PLE studies on post-growth thermally annealed GaAs/Si reveal coexistence of unstrained and strained GaAs.

Low-temperature X-ray diffraction studies on [Cu(4-Xpz)2]x linear chain polymers (where X = Cl, Br, CH3, H; pz = pyrazolate)

1993 ◽  
Vol 71 (3) ◽  
pp. 331-334 ◽  
Author(s):  
Martin K. Ehlert ◽  
Alan Storr ◽  
Robert C. Thompson ◽  
Frederick W. B. Einstein ◽  
Raymond J. Batchelor
Keyword(s):  
Low Temperature ◽  
Room Temperature ◽  
Copper Ions ◽  
Structural Parameters ◽  
Linear Chain ◽  
Crystallographic Axis ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Cell Parameters

Room temperature and low-temperature (110–140 K) powder diffractograms have been obtained for the polymeric compounds [Cu(4-Xpz)2]x (where X = H, CH3, Cl, and Br), and values of the unit cell parameters (orthorhombic, space group Ibam) a, b, and c have been obtained at both high and low temperatures. A single crystal X-ray diffraction study of the X = H compound at 116 K was completed and the results compared with a published study done at room temperature. The structures of these complexes involve extended chains of pyrazolate-bridged copper ions extending along the c crystallographic axis. The X-ray studies indicate little change in the c parameter with decreasing temperature and small but significant changes in the a or b parameters reflecting changes in interchain packing. This study permits some evaluation of how structural parameters are affected by these variations in interchain packing and how these variations may be affecting the magnitude of magnetic exchange in the compounds.

The Effect of Ultra-Low Temperature Treatments on the Stress in Aluminum Metallization on Silicon Wafers

1994 ◽  
Vol 338 ◽  
Author(s):  
Frank Baldwin ◽  
Paul H. Holloway ◽  
Mark Bordelon ◽  
Thomas R. Watkins
Keyword(s):  
Stress Relaxation ◽  
Low Temperature ◽  
Thermal Cycling ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
Silicon Wafers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Aluminum Metallization ◽  
Low Temperature Treatments

ABSTRACTThe stresses in Al-0.75w%Si-0.5w%Cu unpatterned metallization on silicon wafers have been measured using substrate curvature and x-ray diffraction techniques after quenching in liquid nitrogen. Stresses were measured with and without phospho-silicate glass overlayers and SiO2 underlayers, and thermal cycling followed by relaxation at room temperature. It was found that cooling the substrates to 77 K and warming to room temperature caused the metallization stress to go from tensile to compressive. Subsequent heating of the substrates to above ∼70°C followed by cooling to room temperature caused the stress to become tensile. Both compressive and tensile stresses were found to relax at room temperature with a time constant of 2.3 ± 0.2 hours. The magnitude of stress relaxation was a function of temperature, being about 20 MPa after heating to 240°C. The metallization exhibited both compressive and tensile flow stresses of ∼100 MPa near room temperature.

Low-Temperature Performance of the Li[Li0.2Co0.4Mn0.4]O2 Cathode Material Studied for Li-Ion Batteries

2011 ◽  
Vol 347-353 ◽  
pp. 3662-3665 ◽  
Author(s):  
Yu Hui Wang ◽  
Zhe Li ◽  
Kai Zhu ◽  
Gang Li ◽  
Ying Jin Wei ◽  
...  
Keyword(s):  
Low Temperature ◽  
Cathode Material ◽  
Room Temperature ◽  
Sol Gel ◽  
Cycle Performance ◽  
Li Ion Batteries ◽  
X Ray Diffraction ◽  
Capacity Retention ◽  
X Ray ◽  
Li Ion

The Li[Li0.2Co0.4Mn0.4]O2 cathode material was prepared by a sol-gel method. Combinative X-ray diffraction (XRD) studies showed that the material was a solid solution of LiCoO2 and Li2MnO3. The material showed a reversible discharge capacity of 155.0 mAhg−1 at -20 °C, which is smaller than that at room temperature (245.5 mAhg−1). However, the sample exhibited capacity retention of 96.3 % at -20 °C, only 74.2 % at 25 °C. The good electrochemical cycle performance at low temperature was due to the inexistence of Mn3+ in the material.

scholarly journals Influence of Commercial Saturated Monoglyceride, Mono-/Diglycerides Mixtures, Vegetable Oil, Stirring Speed, and Temperature on the Physical Properties of Organogels

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Omar Gerardo Rocha-Amador ◽  
Jose Alberto Gallegos-Infante ◽  
Qingrong Huang ◽  
Nuria Elizabeth Rocha-Guzman ◽  
Martha Rocio Moreno-Jimenez ◽  
...  
Keyword(s):  
Experimental Design ◽  
Light Microscopy ◽  
Physical Properties ◽  
Cooling Rate ◽  
Vegetable Oil ◽  
Polarized Light ◽  
X Ray Diffraction ◽  
Rheological Characterization ◽  
Calorimetric Analysis ◽  
X Ray

The objective of this study was to evaluate the influence of gelator, vegetable oil, stirring speed, and temperature on the physical properties of obtained organogels. They were prepared under varying independent conditions and applying a fractional experimental design. From there a rheological characterization was developed. The physical characterization also included polarized light microscopy and calorimetric analysis. Once these data were obtained, X-Ray diffraction was applied to selected samples and a microstructure lattice was confirmed. Commonly, the only conditions that affect crystallization have been analyzed (temperature, solvent, gelator, and cooling rate). We found that stirring speed is the most important parameter in the organogel preparation.

scholarly journals Research on the physical properties and film removal mechanism of silver brazing flux by micro morphology analysis and X-Ray Diffraction

2021 ◽  
Vol 2083 (2) ◽  
pp. 022085
Author(s):  
Yue Zhao ◽  
Weimin Long ◽  
Sujuan Zhong ◽  
Luyi Wang
Keyword(s):  
Physical Properties ◽  
Melting Temperature ◽  
Removal Mechanism ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphology Analysis ◽  
Micro Morphology

Abstract The effect of KHF2 addition on silver brazing flux was studied in this paper. Results showed that the melting temperature of brazing flux would sustainably decrease with the increasing content of KHF2. KF could not be completely replaced by KHF2 in the brazing flux because it could restrain excessive spreadability, which was resulted from KHF2. F element in the flux replaced O element to form Fe2F5.

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