On the Chemistry of Tetrabenzyl Thiuram Disulfide and Tetramethyl Thiuram Disulfide with Bis (Triethoxysilylpropyl) Tetrasulfide in Silica Compounds

2003 ◽  
Vol 76 (4) ◽  
pp. 876-891 ◽  
Author(s):  
R. N. Datta ◽  
A. G. Talma ◽  
S. Datta ◽  
P. G. J. Nieuwenhuis ◽  
W. J. Nijenhuis ◽  
...  
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Succinic Anhydride ◽  
Dynamic Properties ◽  
The Other ◽  
Resonance Spectroscopy ◽  
Reaction Products ◽  
Negative Effect ◽  
Higher Temperature ◽  
Analytical Tools

Abstract The use of thiurams such as Tetramethyl thiuram disulfide (TMTD) or Tetrabenzyl thiuram disulfide (TBzTD) has been explored to achieve higher cure efficiency. The studies suggest that a clear difference exists between the effect of TMTD versus TBzTD. TMTD reacts with Bis (triethoxysilylpropyl) tetrasulfide (TESPT) and this reaction can take place even at room temperature. On the other hand, the reaction of TBzTD with TESPT is slow and takes place only at higher temperature. High Performance Liquid Chromatography (HPLC) with mass (MS) detection, Nuclear Magnetic Resonance Spectroscopy (NMR) and other analytical tools have been used to understand the differences between the reaction of TMTD and TESPT versus TBzTD and TESPT. The reaction products originating from these reactions are also identified. These studies indicate that unlike TMTD, TBzTD improves the cure efficiency allowing faster cure without significant effect on processing characteristics as well as dynamic properties. The loading of TESPT is reduced in a typical Green tire compound and the negative effect on viscosity is repaired by addition of anhydrides, such as succinic anhydride, maleic anhydride, etc.

scholarly journals Recent Observations on the Mechanical Properties of Polymer Networks

1971 ◽  
Vol 44 (5) ◽  
pp. 1256-1272 ◽  
Author(s):  
P. Thirion ◽  
R. Chasset
Keyword(s):  
Crosslink Density ◽  
Room Temperature ◽  
Dynamic Properties ◽  
Polymer Networks ◽  
The Other ◽  
Dilution Ratio ◽  
Chain Entanglement ◽  
Influence Of Temperature ◽  
Terminal Zone ◽  
Crosslinking Agents

Abstract The influence of temperature, elongation, swelling or dilution ratio, crosslink density, nature of the polymers, and crosslinking agents on the dynamic properties, creep and relaxation of polymer networks is surveyed in the terminal region of the spectrum. Whereas the deformation does not change the relaxation kinetics in large ranges of extension, the crosslink density acts as a reduced variable apparently accelerating uniformly the viscoelastic processes beyond the glass transition. The other possible reductions ‘time-temperature’ and ‘time—swelling’ do not necessarily seem related to the variations of free volume. From the viewpoint of the explanation of the relaxation mechanisms in the terminal zone, the fact that the equilibrium of loosely crosslinked elastomers would only virtually be reached after several years at room temperature seem in better agreement with chain entanglement effects, either trapped or not by the permanent network, than with the dissociation of secondary linkages.

Newly Developed Heat Resistant Magnesium Alloy by Thixomolding®

2005 ◽  
Vol 488-489 ◽  
pp. 287-290 ◽  
Author(s):  
Tadayoshi Tsukeda ◽  
Ken Saito ◽  
Mayumi Suzuki ◽  
Junichi Koike ◽  
Kouichi Maruyama
Keyword(s):  
Aluminum Alloy ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Die Casting ◽  
The Other ◽  
Heat Resistant ◽  
Higher Temperature ◽  
Better Than

We compared the newly developed heat resistant magnesium alloy with conventional ones by Thixomolding® and aluminum alloy by die casting. Tensile properties at elevated temperatures of AXEJ6310 were equal to those of ADC12. In particular, elongation tendency of AXEJ6310 at higher temperature was better than those of the other alloys. Creep resistance of AXEJ6310 was larger than that of AE42 by almost 3 orders and smaller than that of ADC12 by almost 2 orders of magnitude. Fatigue limits at room temperature and 423K of AXEJ6310 was superior among conventional magnesium alloys.

scholarly journals EFFECT OF USING L-ASPARAGINASE IN REDUCING ACRYLAMIDE PERCENTAGE IN BISICUT

2016 ◽  
Vol 47 (4) ◽  
Author(s):  
Jebur & et al.
Keyword(s):  
High Performance Liquid Chromatography ◽  
Enzyme Activity ◽  
Liquid Chromatography ◽  
High Performance ◽  
Specific Activity ◽  
Control Sample ◽  
The Other ◽  
Enzyme Efficiency ◽  
Negative Effect ◽  
The Stability

This study was aimed to know the efficiency of partially purified L- asparaginase produced from local isolate from Erwinia spp. to reduce the percentage of acrylamide formed in Biscuit. Four types of biscuit from wheat flour were prepared (T1, T2, T3, T4),and T1 as control. High performance liquid chromatography technique was used to estimate acrylamide ratio in biscuit , Effect of enzyme addition  on flour chemical and rheological properties was studied, also dough behavior ,gluten percentage, water absorption and amylase enzyme activity was estimated. The results revealed  that  the  addition of  experimental asparaginase ( specific activity 20.5 unite mg-1 ) with 1% of flour weight lead to reduce in acrylamide formation in Biscuit  to 89 %  compared  to  control sample ( in absence of enzyme ) . Moreover, the addition of Asparagine to flour at 0.1 % of its weight, where L- asparaginase was available caused a negative effect on enzyme efficiency in reducing the acrylamide in biscuit. So the level of acrylamide was reduced to 57.7 %. In the other hand , the percentage of acryl amide in biscuit was increased to   233 % when the asparagine was added to mixture in absence of L- asparaginase .Addition of  the enzyme to flour have no effect on the percentage value of gluten but improved the  stability of dough .The  enzyme  addition also led to increase amylases activities.  Addition of experimental enzyme had no effect on quality and sensory evaluation of biscuit.

scholarly journals Effect of storage on the fatty acids of dried ryegrass

1967 ◽  
Vol 21 (3) ◽  
pp. 599-608 ◽  
Author(s):  
J. W. Czerkawski
Keyword(s):  
Fatty Acids ◽  
Linolenic Acid ◽  
Dry Matter ◽  
Room Temperature ◽  
The Other ◽  
Mould Growth ◽  
Total Fatty Acids ◽  
Higher Temperature ◽  
Types Of Change ◽  
Oleic And Linoleic Acids

1. The compositions of the fatty acids in ryegrass were determined in fresh samples, and in samples dried at room temperature for 26 h, at 50° and for 18 h or at 100° for 12 h. The drying of grass resulted in a small increase in palmitic acid and a decrease in linolenic acid in the total fatty acids.2. Samples of grass dried at 50° and 100° were stored at three relative humidities (rh < 3%, 47% and 80%) for 13 months.3. There were marked changes in the samples stored at 80% rh, with an onset of mould growth and a loss of dry matter. The samples stored at lower humidities had no mould.4. There were two types of change in the fatty acids during storage. The deterioration brought about and mould was accompanied by a decrease in the concentration of linolenic acid and an increase in the concentrations of oleic and linoleic acids. The other type of change observed at the lower humidities resulted in a decrease in the content of linolenic and an increase in the content of palmitic, and did not affect the amounts of oleic and linoleic cells.5. There was little difference between the changes that occurred in the composition of the total fatty acids of the grass dried at 50° and of that dried at 100°. The changes that were at all significant appeared to occur less rapidly, particularly in the early months of storage, in the grass dried at the higher temperature for the shorter time.

THE ACTION OF CARBON DISULPHIDE ON ALUMINA GEL

1933 ◽  
Vol 9 (5) ◽  
pp. 424-431 ◽  
Author(s):  
L. A. Munro ◽  
J. W. McCubbin
Keyword(s):  
Room Temperature ◽  
Carbon Disulphide ◽  
Residual Water ◽  
Reaction Products ◽  
Yellow Color ◽  
Alumina Gel ◽  
Yellow Coloration ◽  
Higher Temperature ◽  
Carbonyl Sulphide ◽  
By Products

The authors have investigated the yellow color observed when carbon disulphide was adsorbed by c.p. alumina at room temperature. The color is due to by-products of the reactions of carbon disulphide with residual water in the gel. The investigators of the CS2 + H2O reaction at higher temperature attribute the yellow to sulphur or aluminium sulphide. The color formed at room temperature is not due to either of these. The reaction products consist largely of hydrogen sulphide, water, and carbon dioxide, with small amounts of carbonyl sulphide and carbon monoxide. The yellow coloration has been found to be a mixture of sodium sulphide, sodium hydrosulphide, and sodium polysulphide. A mechanism is proposed for its formation.

Joining of Silicon Nitride to Metal (Mo and Ti) Using a Cu-Foil Interlayer

2006 ◽  
Vol 509 ◽  
pp. 99-104 ◽  
Author(s):  
José G. Flores ◽  
José Cervantes ◽  
José Lemus-Ruiz
Keyword(s):  
Silicon Nitride ◽  
Diffusion Bonding ◽  
The Other ◽  
Reaction Products ◽  
Interface Formation ◽  
High Affinity ◽  
Higher Temperature ◽  
Reactive Interface ◽  
Cu Foil ◽  
Foil Interlayer

This work focuses on various aspects of diffusion bonding silicon nitride to Mo and Ti using a Cu-foil interlayer. Si3N4/Cu/Ti/Cu/Si3N4 and Si3N4/Cu/Mo/Cu/Si3N4 combinations have been diffusion joined at temperatures ranging from 950 to 1150 °C using different holding times in Ar. The results show that Si3N4 could not be bonded to Mo at temperature lower than 1100 °C even for holding times of 60 minutes, however, successful joining is achieved at 1150 °C. On the other hand, successful joining is accomplished at 1050 and 1100 °C for a Si3N4/Cu/Ti/Cu/Si3N4 sample. In the Si3N4/Cu/Ti system, joining occurs by the formation of a reactive interface with several reaction products on the metal side of the joint. All the silicon nitride samples have joined to titanium with no several interfacial cracking and porosity at the interface. The results corresponding to the Si3N4/Cu/Mo system show that a higher temperature is required to join the materials compared with the Si3N4/Cu/Ti system, since the formation of liquid produced by the interaction of Cu with Ti and Si promotes bonding and the high affinity of Ti for Si results in rapid interface formation.

scholarly journals Synthesis and NMR spectroscopic characterization of Si-substituted 1-silacyclobutene derivatives

2011 ◽  
Vol 9 (1) ◽  
pp. 126-132 ◽  
Author(s):  
Ezzat Khan ◽  
Bernd Wrackmeyer
Keyword(s):  
Magnetic Resonance ◽  
Room Temperature ◽  
Spectroscopic Characterization ◽  
The Other ◽  
Resonance Spectroscopy ◽  
29Si Nmr ◽  
Reaction Conditions ◽  
New Compounds ◽  
Substituted 1

AbstractHydroboration of trialkyn-1-yl(organo)silanes with one equivalent and two equivalents of 9-borabicyclo[3.3.1]nonane, 9-BBN afford dialkyn-1-ylsilanes and alkyn-1-ylsilanes, respectively. The alkyn-1-ylsilane derivatives are stable at room temperature and can be store under dry argon for prolong period of time. These compounds are attractive materials for further rearrangements to afford novel 1-silacyclobutene derivatives bearing Si-alkenyl or Si-alkynyl functionalities. The hydroboration reaction is well controlled by the Si-R1 function, i.e., the starting silanes with R1 = Ph selectively afford hydroboration of one Si-C≡C bond with one equivalent of 9-BBN, leaving the other two functionalities untouched. Under mild reaction conditions (25°C), the starting silanes with R1 = Me lead to mixture containing dialkyn-1-ylsilane, alkyn-1-ylsilane and their respective 1-silacyclobutene derivatives. All new compounds are sensitive towards air and moisture and were studied by multinuclear magnetic resonance spectroscopy (1H, 13C, 11B, 29Si NMR) in solution.

scholarly journals A Tale of Two Transitions: Unraveling Two Distinct Polymorph Transition Mechanisms in One n-Type Single Crystal for Dynamic Electronics

2021 ◽  
Author(s):  
Daniel W. Davies ◽  
Sang Kyu Park ◽  
Stephen B. Shiring ◽  
Hyunjoong Chung ◽  
Prapti Kafle ◽  
...  
Keyword(s):  
Single Crystal ◽  
Growth Mechanism ◽  
High Performance ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Nucleation And Growth ◽  
The Other ◽  
Resonance Spectroscopy ◽  
Other Hand ◽  
Nucleation And Growth Mechanism

Cooperativity is used by living systems to circumvent energetic and entropic barriers to yield highly efficient molecular processes. Cooperative structural transitions involve the simultaneous, concerted displacement of molecules in a crystalline material, in stark contrast to the more typical molecule-by-molecule nucleation and growth mechanism often breaking the single crystallinity. Cooperative transitions have acquired much attention in the research community for their low transition barriers, ultrafast kinetics, and structural reversibility. On the other hand, cooperative transitions are rarely observed in molecular crystals and the molecular origin is not well understood. Single crystals of 2-dimensional quinoidal terthiophene (2DQTT-o-B), a high-performance n-type organic semiconductor, demonstrate two thermally-activated, reversible phase transitions with one exhibiting a cooperative mechanism and the second exhibiting a nucleation and growth mechanism. In situ microscopy, single crystal and grazing incidence X-ray diffraction (GIXD), along with Raman spectroscopy suggest a reorientation of the alkyl side chains results in a cooperative transition behavior. On the other hand, the nucleation and growth transition is coincident with both side chain melting and the emergence of new spin-spin interactions between conjugated cores, confirmed through in situ electron paramagnetic resonance spectroscopy (EPR). This is the first observation of biradical interactions directly initiating a structural transition. Through studying these fundamental mechanisms, we establish alkyl chain conformation and disorder as integral to rationally controlling these polymorphic behaviors for novel electronic applications.

Magnetic and Electric Properties of Phase Separated Glass Ceramics in CoO–TiO2–SiO2 System Prepared by Melt Quenching Process

2008 ◽  
Vol 1118 ◽  
Author(s):  
Hiroki Nakamura ◽  
Tetsuo Kishi ◽  
Yuji Muro ◽  
Ryuji Tamura ◽  
Kazuyasu Tokiwa ◽  
...  
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Glassy Phase ◽  
Glass Ceramics ◽  
The Other ◽  
Melt Quenching ◽  
Nano Structure ◽  
Quenching Process ◽  
Magnetic And Electric Properties ◽  
Co Doped

ABSTRACTThe developments of high performance magnetic materials are required in various applications such as high sensitive magnetic sensing and hyperthermia in cancer treatment. Recently, Co-doped TiO2 has been received considerable attention as a candidate for such materials because of their ferromagnetic properties at room temperature. On the other hand, the phase-separated glasses and the derived glass-ceramics having unique micro-nano structure are utilized for various applications. In this study, the phase separated glass-ceramics in CoO-TiO2-SiO2 system with Al2O3 addition were prepared by melt-quenching process. The as-quenched samples consisted of the TiO2-rich phase and the SiO2-rich one which were formed by a nucleation-growth mechanism of phase separation. From the results of XRD measurements, the samples were found to have a TiO2 crystalline phase and a SiO2-rich glassy phase. The samples showed the magnetic property, which were regarded as a mixture of ferromagnetic and paramagnetic phases. The samples also showed the electric conductivity at room temperature. However, the conductivity of the sample decreased with increase of the Co content, and the temperature dependence of the conductivity of the ferromagnetic samples was different from the other ones. As a result, the Co ions in the phase-separated glass-ceramics in TiO2-SiO2 system were found to affect on both the magnetic and the electric conductive characteristics.

scholarly journals RECENT ADVANCES IN TITANIUM TECHNOLOGY IN THE UNITED STATES

2020 ◽  
Vol 321 ◽  
pp. 01007
Author(s):  
Dongjian(Don) Li ◽  
Vasisht Venkatesh
Keyword(s):  
High Performance ◽  
Dynamic Properties ◽  
The United States ◽  
Modeling Tools ◽  
Technology Products ◽  
The Us ◽  
Substantial Progress ◽  
Current Production ◽  
Higher Temperature ◽  
Research Facilities

Substantial progress has continued in the US since the last (13th) World Titanium Conference with regards to titanium technology, products, processing, computational modeling tools and applications. Titanium components produced by additive manufacturing have been qualified and achieved production applications in commercial and military aircraft hardware. New high-performance titanium alloys have been developed for higher temperature service and applications requiring more demanding static and dynamic properties. Current production processes for titanium have been optimized, and new processes have been developed to further reduce cost and improve product quality. Titanium suppliers, OEM’s, government labs and academia are working closely together to address fundamental industry-wide issues. Computer modeling is now used extensively in industrial and research facilities to accelerate the pace and success of these developments.

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