scholarly journals Effect of MMT Clay Content on Thermal Behaviour of MDPE/MMT Nanocomposite

2010 ◽  
Vol 19 (5) ◽  
pp. 096369351001900
Author(s):  
J. Sargolzaei ◽  
M. Tavakol ◽  
Akbarabady
Keyword(s):  
Ammonium Salt ◽  
Room Temperature ◽  
Clay Content ◽  
Decomposition Temperature ◽  
Temperature Range ◽  
Air Atmosphere ◽  
Uniform Dispersion ◽  
Wide Range ◽  
Mmt Clay ◽  
Alkyl Ammonium

The thermal stability of medium-density polyethylene (MDPE)/Montmorillonite nanocomposite was studied by TGA and DSC methods in a wide range of temperature. The dispersion of the MMT clays on microscopic scales was examined using a Transmission electron microscopy (TEM). The mass loss from thermogravimetric analysis (TGA) was used to study decomposition temperature in a temperature range from room temperature to 800 °C and DSC was used to probe melting and crystallization in a temperature range from room temperature to 300°C. Simultaneous TGA made possible to show that non modified MMT clay and MMT clay modified with alkyl ammonium salt exhibit a significant stabilizing effect on MDPE macromolecules in air atmosphere and DSC shows natural MMT and MMT clay modified with alkyl ammonium salt exhibit a significant change in melting, crystallization, enthalpy and crystalline content of samples. TEM image shows uniform dispersion and intercalation of MMT clays in nanocomposites.

Porphyrin-Catalyzed Oxidation of N-Substituted Tetrahydroisoquinolines to Dihydroisoquinolones

Synlett ◽  
2021 ◽  
Author(s):  
Ao Li ◽  
Bin Pan ◽  
Mu Chao ◽  
Na Wang ◽  
Yu-Long Li ◽  
...  
Keyword(s):  
Visible Light ◽  
Room Temperature ◽  
Air Atmosphere ◽  
Wide Range ◽  
Convenient Route ◽  
Catalyzed Oxidation

A visible-light-induced direct α-oxygenation of N-substituted tetrahydroisoquinoline derivatives has been successfully developed. Metalloporphyrin (ZnTPP) has been identified as an effective and inexpensive photocatalyst for this transformation with a wide range of substrates. This protocol provides a convenient route to afford the desired products in moderate to good yields at room temperature under air atmosphere.

scholarly journals Thermal, Morphological Analysis of Epoxy/Unsaturated Polyester Blended Nanocomposite with Wollastonite Powder as a Particulate

2019 ◽  
Vol 31 (9) ◽  
pp. 2069-2072
Author(s):  
A. Damodara Reddy ◽  
M.L.S. Deva Kumar
Keyword(s):  
Morphological Analysis ◽  
Polyester Resin ◽  
Unsaturated Polyester ◽  
Morphological Structure ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Research Article ◽  
Uniform Dispersion ◽  
Wide Range ◽  
Microscopy Images

In the proposed research article, polymer nanocomposites on the basis of thermoset polymer resultant blends (epoxy/polyester) having wollastonite powder are prepared by high shear mixer (mechanical), followed by an ultra-sonicator for uniform dispersion of wollastonite particulates in the final blend matrix. Wide range percentages of modified wollastonite nano-particulates with 0, 1, 2, 3, 4 and 5 wt. % were incorporated into the epoxy/polyester blend matrix in order to evaluate the effect of nanofillers on nanophase morphological structure and to study material properties. Various thermal parameters of the nanocomposite were evaluated using thermogravimetric analysis and differential scanning calorimetry techniques. Further, the scanning electron microscopy images have been employed to know fractured surfaces of the titled compound. From the experimental data it was found that uniform miscibility of epoxy/polyester blend mix and homogenous dispersion of wollastonite nano particulates in the blend matrix was noticed. From the TGA studies, 8 % weight loss and 4 °C rise in decomposition temperature was observed with addition of 5 wt. % wollastonite when compared with the 0 wt. % wollastonite combination of epoxy/unsaturated polyester resin blend. DSC results further revealed that the modified wollastonite nanoparticles is major responsible for the glass transition temperature (Tg) of the nanocomposites.

scholarly journals THERMAL CONDUCTIVITY OF COMPOSITIONS BASED ON A SILOXANE BINDER WITH A HIGH FILLER CONTENT OF ALUMINUM HYDROXIDE POWDER

2018 ◽  
pp. 39-43
Author(s):  
V. Sh. Sulaberidze ◽  
V. D. Mushenko ◽  
V. A. Mikheev
Keyword(s):  
Thermal Conductivity ◽  
Composite Materials ◽  
Aluminum Hydroxide ◽  
Volume Content ◽  
Room Temperature ◽  
Filler Content ◽  
Heat Conducting ◽  
Temperature Range ◽  
Wide Range ◽  
Volumetric Content

The use of aluminum hydroxide as a filler in composite materials makes them non-flammable. When the thermal conductivity of such compositions is above 1 W/(m-K), they can be used as heat-conducting insulating and non-flammable coatings in power electronics. Thermal conductivity of compositions based on dimethylsiloxane with a filler made from aluminum hydroxide powders of various dissipation is studied in the temperature range from 25 °C to 200 °C, depending on the volume content of the filler. With a volumetric content of filler up to 60%, no significant differences in the values of the thermal conductivity of samples with powders of the investigated fractional groups were detected. With volumetric content of the filler more than 40%, the thermal conductivity of the composition at room temperature exceeded 1 W/(m-K). It is shown that the Burger formula modified by the authors turned out to be sufficiently universal for the calculated estimates of the thermal conductivity of materials with different fillers in a wide range of their volume contents.

Rare Earth and Perovskite Composite Ceramics Applied for the Thermistor with Wide Temperature Range

2012 ◽  
Vol 512-515 ◽  
pp. 613-616 ◽  
Author(s):  
Bo Zhang ◽  
Qing Zhao ◽  
Ai Min Chang ◽  
Peng Jun Zhao ◽  
Fang Guan
Keyword(s):  
Wide Temperature Range ◽  
Perovskite Phase ◽  
Temperature Characteristic ◽  
Absolute Temperature ◽  
Composite Ceramics ◽  
Conventional Solid State Reaction ◽  
Temperature Range ◽  
Air Atmosphere ◽  
Wide Range ◽  
Ntc Thermistors

Different compositions (aY2O3+bCeO2)-0.4YCr0.5Mn0.5O3 (a+b=0.6) were prepared via a conventional solid-state reaction at 1200°C, and sintered under air atmosphere at 1600°C. XRD patterns analysis has revealed that for 0<a<0.6, the major phases present in the calcined bodies are Y2O3, CeO2 and orthorhombic perovskite YCr0.5Mn0.5O3 phase, respectively. SEM and EDAX observations confirm the obtaining of three-phased composite ceramics. The brighter regions are the Y2O3 and CeO2 phase, whereas the darker are perovskite phase. All the NTC thermistors prepared show a similar linear relationship between the ln of the resistance and the reciprocal of the absolute temperature, indicative of NTC characteristics. For 0≤a≤0.6, the plotting curves of resistance- temperature characteristic are none linear on the wide temperature range, exhibit two branches. The obtained B25/150 and B700/1000 constants of the thermistors are in the range 3600-4400K and 6700-12000K. The magnitude order of the resistivity at 25°C is of 106-107Ωcm and activation energies vary from 0.313 to 1.029 eV at low and high temperatures, respectively. These compounds, having good NTC characteristics in a wide range of temperatures, could be applied as potential candidates for NTC thermistors from ambient to 1100°C.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

Evaluation of 99mTc-Label led Vitamin K4 as an Agent for Testicular Imaging

1991 ◽  
Vol 30 (01) ◽  
pp. 35-39 ◽  
Author(s):  
H. S. Durak ◽  
M. Kitapgi ◽  
B. E. Caner ◽  
R. Senekowitsch ◽  
M. T. Ercan
Keyword(s):  
Soft Tissue ◽  
Room Temperature ◽  
Normal Subjects ◽  
Left Testis ◽  
Wide Range ◽  
Activity Ratios ◽  
The Right ◽  
Radioactivity Levels

Vitamin K4 was labelled with 99mTc with an efficiency higher than 97%. The compound was stable up to 24 h at room temperature, and its biodistribution in NMRI mice indicated its in vivo stability. Blood radioactivity levels were high over a wide range. 10% of the injected activity remained in blood after 24 h. Excretion was mostly via kidneys. Only the liver and kidneys concentrated appreciable amounts of radioactivity. Testis/soft tissue ratios were 1.4 and 1.57 at 6 and 24 h, respectively. Testis/blood ratios were lower than 1. In vitro studies with mouse blood indicated that 33.9 ±9.6% of the radioactivity was associated with RBCs; it was washed out almost completely with saline. Protein binding was 28.7 ±6.3% as determined by TCA precipitation. Blood clearance of 99mTc-l<4 in normal subjects showed a slow decrease of radioactivity, reaching a plateau after 16 h at 20% of the injected activity. In scintigraphic images in men the testes could be well visualized. The right/left testis ratio was 1.08 ±0.13. Testis/soft tissue and testis/blood activity ratios were highest at 3 h. These ratios were higher than those obtained with pertechnetate at 20 min post injection.99mTc-l<4 appears to be a promising radiopharmaceutical for the scintigraphic visualization of testes.

scholarly journals Preparation and Gas Sensing Properties of PANI/SnO2 Hybrid Material

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1360
Author(s):  
Qiaohua Feng ◽  
Huanhuan Zhang ◽  
Yunbo Shi ◽  
Xiaoyu Yu ◽  
Guangdong Lan
Keyword(s):  
Hybrid Material ◽  
Room Temperature ◽  
Tin Dioxide ◽  
Gas Adsorption ◽  
Gas Sensing ◽  
Oxidative Polymerization ◽  
Environmental Pollutants ◽  
Decomposition Temperature ◽  
Benzene Vapor ◽  
Thermo Gravimetric Analyzer

A sensor operating at room temperature has low power consumption and is beneficial for the detection of environmental pollutants such as ammonia and benzene vapor. In this study, polyaniline (PANI) is made from aniline under acidic conditions by chemical oxidative polymerization and doped with tin dioxide (SnO2) at a specific percentage. The PANI/SnO2 hybrid material obtained is then ground at room temperature. The results of scanning electron microscopy show that the prepared powder comprises nanoscale particles and has good dispersibility, which is conducive to gas adsorption. The thermal decomposition temperature of the powder and its stability are measured using a differential thermo gravimetric analyzer. At 20 °C, the ammonia gas and benzene vapor gas sensing of the PANI/SnO2 hybrid material was tested at concentrations of between 1 and 7 ppm of ammonia and between 0.4 and 90 ppm of benzene vapor. The tests show that the response sensitivities to ammonia and benzene vapor are essentially linear. The sensing mechanisms of the PANI/SnO2 hybrid material to ammonia and benzene vapors were analyzed. The results demonstrate that doped SnO2 significantly affects the sensitivity, response time, and recovery time of the PANI material.

Enabling highly reversible sodium metal cycling across a wide temperature range with dual-salt electrolytes

2021 ◽  
Author(s):  
Akila C. Thenuwara ◽  
Pralav P. Shetty ◽  
Neha Kondekar ◽  
Chuanlong Wang ◽  
Weiyang Li ◽  
...  
Keyword(s):  
Wide Temperature Range ◽  
High Energy ◽  
Liquid Electrolyte ◽  
Metal Cycling ◽  
Temperature Range ◽  
Sodium Metal ◽  
Wide Range

A new dual-salt liquid electrolyte is developed that enables the reversible operation of high-energy sodium-metal-based batteries over a wide range of temperatures down to −50 °C.

scholarly journals A Characteristic Study of Polylactic Acid/Organic Modified Montmorillonite (PLA/OMMT) Nanocomposite Materials after Hydrolyzing

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 376
Author(s):  
Su-Mei Huang ◽  
Jiunn-Jer Hwang ◽  
Hsin-Jiant Liu ◽  
An-Miao Zheng
Keyword(s):  
Thermal Stability ◽  
Polylactic Acid ◽  
Decomposition Temperature ◽  
Material Strength ◽  
Scanning Calorimetry ◽  
Hydrolysis Process ◽  
Twin Screw ◽  
Thermal Pressing ◽  
Organophilic Clay ◽  
Mmt Clay

In this study, the montmorillonite (MMT) clay was modified with NH4Cl, and then the structures were exfoliated or intercalated in a polylactic acid (PLA) matrix by a torque rheometer in the ratio of 0.5, 3.0, 5.0 and 8.0 wt%. X-ray diffraction (XRD) revealed that the organic modified-MMT(OMMT) was distributed successfully in the PLA matrix. After thermal pressing, the thermal stability of the mixed composites was measured by a TGA. The mixed composites were also blended with OMMT by a co-rotating twin screw extruder palletizing system, and then injected for the ASTM-D638 standard specimen by an injection machine for measuring the material strength by MTS. The experimental results showed that the mixture of organophilic clay and PLA would enhance the thermal stability. In the PLA mixed with 3 wt% OMMT nanocomposite, the TGA maximum decomposition temperature (Tmax) rose from 336.84 °C to 339.08 °C. In the PLA mixed with 5 wt% OMMT nanocomposite, the loss of temperature rose from 325.14 °C to 326.48 °C. In addition, the elongation rate increased from 4.46% to 10.19% with the maximum loading of 58 MPa. After the vibrating hydrolysis process, the PLA/OMMT nanocomposite was degraded through the measurement of differential scanning calorimetry (DSC) and its Tg, Tc, and Tm1 declined.

scholarly journals Plasmonic semiconductor nanogroove array enhanced broad spectral band millimetre and terahertz wave detection

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Jinchao Tong ◽  
Fei Suo ◽  
Tianning Zhang ◽  
Zhiming Huang ◽  
Junhao Chu ◽  
...  
Keyword(s):  
Surface Plasmon ◽  
High Performance ◽  
Room Temperature ◽  
Spectral Band ◽  
High Capacity ◽  
Terahertz Wave ◽  
Semiconductor Surface ◽  
Wide Range ◽  
Low Sensitivity ◽  
Air Interfaces

AbstractHigh-performance uncooled millimetre and terahertz wave detectors are required as a building block for a wide range of applications. The state-of-the-art technologies, however, are plagued by low sensitivity, narrow spectral bandwidth, and complicated architecture. Here, we report semiconductor surface plasmon enhanced high-performance broadband millimetre and terahertz wave detectors which are based on nanogroove InSb array epitaxially grown on GaAs substrate for room temperature operation. By making a nanogroove array in the grown InSb layer, strong millimetre and terahertz wave surface plasmon polaritons can be generated at the InSb–air interfaces, which results in significant improvement in detecting performance. A noise equivalent power (NEP) of 2.2 × 10−14 W Hz−1/2 or a detectivity (D*) of 2.7 × 1012 cm Hz1/2 W−1 at 1.75 mm (0.171 THz) is achieved at room temperature. By lowering the temperature to the thermoelectric cooling available 200 K, the corresponding NEP and D* of the nanogroove device can be improved to 3.8 × 10−15 W Hz−1/2 and 1.6 × 1013 cm Hz1/2 W−1, respectively. In addition, such a single device can perform broad spectral band detection from 0.9 mm (0.330 THz) to 9.4 mm (0.032 THz). Fast responses of 3.5 µs and 780 ns are achieved at room temperature and 200 K, respectively. Such high-performance millimetre and terahertz wave photodetectors are useful for wide applications such as high capacity communications, walk-through security, biological diagnosis, spectroscopy, and remote sensing. In addition, the integration of plasmonic semiconductor nanostructures paves a way for realizing high performance and multifunctional long-wavelength optoelectrical devices.

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