scholarly journals Effect of Urea Concentration on the Viscosity and Thermal Stability of Aqueous NaOH/Urea Cellulose Solutions

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Tim Huber ◽  
Katherine Starling ◽  
Wanwen (Samantha) Cen ◽  
Conan Fee ◽  
Simone Dimartino
Keyword(s):  
Thermal Stability ◽  
Quartz Crystal ◽  
Direct Interaction ◽  
Cellulose Powder ◽  
Gelation Temperature ◽  
Direct Role ◽  
Cross Linker ◽  
Urea Inclusion ◽  
Thermal Stability Of ◽  
Urea Inclusion Complex

Aqueous solutions of sodium hydroxide (NaOH) and urea are a known and versatile solvent for cellulose. The dissolution of cellulose occurs at subambient temperatures through the formation of a cellulose-NaOH-urea “inclusion complex” (IC). NaOH and urea form a hydrate layer around the cellulose chains preventing chain agglomeration. Urea is known to stabilize the solution but its direct role is unknown. Using viscometry and quartz crystal microbalance with dissipation monitoring (QCM-D) it could be shown that the addition of urea reduced the solutions viscosity of the tested solutions by almost 40% and also increased the gelation temperature from approximately 40°C to 90°C. Both effects could also be observed in the presence of additional cellulose powder serving as a physical cross-linker. Using Fourier transform infrared (FTIR) spectroscopy during heating, it could be shown that a direct interaction occurs between urea and the cellulose molecules, reducing their ability to form hydrogen bonds with neighbouring chains.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Microstructure studies of tungsten silicide schottky contacts on Gaas

1987 ◽  
Vol 45 ◽  
pp. 328-329
Author(s):  
Yih-Cheng Shih ◽  
E. L. Wilkie
Keyword(s):  
Thermal Stability ◽  
Field Effect Transistors ◽  
Schottky Contact ◽  
Schottky Contacts ◽  
Excellent Thermal Stability ◽  
Barrier Heights ◽  
Gaas Substrates ◽  
Film Adhesion ◽  
Threshold Voltages ◽  
Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

Thermal stability of Al-Cu-Fe icosahedral alloys

1991 ◽  
Vol 1 (12) ◽  
pp. 1823-1836 ◽  
Author(s):  
M. Bessière ◽  
A. Quivy ◽  
S. Lefebvre ◽  
J. Devaud-Rzepski ◽  
Y. Calvayrac
Keyword(s):  
Thermal Stability ◽  
Thermal Stability Of

Practical criteria for the thermal stability of a unidimensional superconductor

1994 ◽  
Vol 4 (4) ◽  
pp. 653-657
Author(s):  
B. Bonzi ◽  
M. El Khomssi ◽  
H. Lanchon-Ducauquis
Keyword(s):  
Thermal Stability ◽  
Thermal Stability Of

Time and thermal stability of magnetic properties of amorphous Fe80TM3B17 alloys

1998 ◽  
Vol 08 (PR2) ◽  
pp. Pr2-63-Pr2-66 ◽  
Author(s):  
R. Varga ◽  
P. Vojtaník ◽  
A. Lovas
Keyword(s):  
Thermal Stability ◽  
Magnetic Properties ◽  
Thermal Stability Of

Thermal stability of organic-inorganic nanocomposites based on system of dimethacrylate-tetraethoxysilane and their kinetic features

2016 ◽  
Vol 38 (3) ◽  
pp. 211-217
Author(s):  
G.I. Khovanets’ ◽  
◽  
O.Y. Makido ◽  
V.V. Kochubey ◽  
Y.G. Medvedevskikh ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Inorganic Nanocomposites ◽  
Thermal Stability Of ◽  
Kinetic Features

The effect of salicylates on nonenzymatic glycosylation and thermal stability of collagen in diabetic rats

Diabetes ◽  
1984 ◽  
Vol 33 (8) ◽  
pp. 745-751 ◽  
Author(s):  
D. K. Yue ◽  
S. McLennan ◽  
D. J. Handelsman ◽  
L. Delbridge ◽  
T. Reeve ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Diabetic Rats ◽  
Nonenzymatic Glycosylation ◽  
Thermal Stability Of
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