scholarly journals Thermal Degradation of Polystyrene (PS) Nanocomposites Loaded with Sol Gel-Synthesized ZnO Nanorods

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1935
Author(s):  
Ashraf H. Farha ◽  
Abdullah F. Al Naim ◽  
Shehab A. Mansour
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Zno Nanoparticles ◽  
Sol Gel ◽  
Zno Nanorods ◽  
Casting Method ◽  
Scanning Calorimetry ◽  
The Common ◽  
Constant Heating ◽  
Thermal Stability Of

Thermal degradation of polystyrene/ZnO (PS/ZnO) nanocomposites was investigated in this study. PS/ZnO polymer nanocomposites were prepared by using ZnO nanorods as nanofillers that were prepared via the sol-gel route. The as-prepared ZnO nanoparticles showed nanocrystallites in rod-like shapes with a non-uniform hexagonal cross-section and diameter varying from 40 to 75 nm. PS/ZnO nanocomposites with ZnO nanoparticles content ranging from 0–3 wt% are prepared via the common casting method. Even dispersion for ZnO nanoparticles within as-prepared PS/ZnO nanocomposites was verified through SEM/EDX measurements. Thermal degradation of the samples was checked by using the thermogravimetric (TG) analysis and differential scanning calorimetry (DSC) under non-isothermal conditions and a constant heating rate of 10 °C min. The thermal stability of the nanocomposite is elevated compared to that of pristine PS due to the addition of the ZnO nanoparticles. The homogeneity of the PS/ZnO nanocomposites is verified by systematic increases in thermal degradation with increasing ZnO content. The characterization degradation temperatures at different weight loss percentages of ZnO nanoparticles increase at high ZnO wt%. Static activation energy of decomposing is based on TGA data. Activation energies showed some enhancement after the addition of ZnO nanorods into the PS matrix. Enhancing the thermal stability of PS with ZnO addition within the investigated ZnO concentration range is verified by TG, DSC results.

scholarly journals Development of Novel Silica-Based Formulation of α-Lipoic Acid: Evaluation of Photo and Thermal Stability of the Encapsulated Drug

Pharmaceutics ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 228 ◽  
Author(s):  
Ekaterina S. Dolinina ◽  
Elizaveta Yu. Akimsheva ◽  
Elena V. Parfenyuk
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Lipoic Acid ◽  
Sol Gel ◽  
Silica Matrix ◽  
Matrix Modification ◽  
Drug Stabilization ◽  
Further Development ◽  
Kinetics Of ◽  
Thermal Stability Of

Powerful antioxidant α-lipoic acid (LA) is easily degraded under light and heating. This creates difficulties in its manufacture, storage and reduces efficiency and safety of the drug. The purpose of this work was to synthesize novel silica-based composites of LA and evaluate their ability to increase photo and thermal stability of the drug. It was assumed that the drug stabilization can be achieved due to LA-silica interactions. Therefore, the composites of LA with unmodified and organomodified silica matrixes were synthesized by sol-gel method at the synthesis pH below or above the pKa of the drug. The effects of silica matrix modification and the synthesis pH on the LA-silica interactions and kinetics of photo and thermal degradation of LA in the composites were studied. The nature of the interactions was revealed by FTIR spectroscopy. It was found that the rate of thermal degradation of the drug in the composites was significantly lower compared to free LA and mainly determined by the LA-silica interactions. However, photodegradation of LA in the composites under UV irradiation was either close to that for free drug or significantly more rapid. It was shown that kinetics of photodegradation was independent of the interactions and likely determined by physical properties of surface of the composite particles (porosity and reflectivity). The most promising composites for further development of novel silica-based formulations were identified.

Retarded Cross-linking in ZnO-low-density Polyethylene Nanocomposites

2002 ◽  
Vol 17 (5) ◽  
pp. 940-943 ◽  
Author(s):  
J.I. Hong ◽  
K. S. Cho ◽  
C. I. Chung ◽  
L. S. Schadler ◽  
R. W. Siegel
Keyword(s):  
Thermal Stability ◽  
Thermal Properties ◽  
Thermal Degradation ◽  
Surface Properties ◽  
Zno Nanoparticles ◽  
Low Density Polyethylene ◽  
Cross Linking ◽  
Low Density ◽  
Zno Particles ◽  
Thermal Stability Of

ZnO nanoparticles were mixed with branched low-density polyethylene and were found to increase the resistance of the polymer to thermal degradation without changing other thermal properties. Submicron-size ZnO particles were mixed with low-density polyethylene for comparison, and it was found that the increased thermal stability of the nanocomposite was due to the surface properties of nanoparticles smaller than approximately 100 nm in diameter.

Thermal Analysis of Chitosan-Lactate and Chitosan-Aluminum Monostearate Composite System

2012 ◽  
Vol 506 ◽  
pp. 278-281 ◽  
Author(s):  
Kotchamon Yodkhum ◽  
T. Phaechamud
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Thermal Degradation ◽  
Chitosan Solution ◽  
Melting Behavior ◽  
Degradation Behavior ◽  
Scanning Calorimetry ◽  
Chitosan Derivatives ◽  
Thermal Degradation Behavior ◽  
Thermal Stability Of

Chitosan possess many attractive properties for applying as biomaterials. For some application, biomaterial devices have to be sterilized using high temperature, e.g. stream sterilizing process. However, thermal degradation behavior of chitosan has been reported previously. Many researchers have attempted to improve thermal degradation behavior of chitosan by synthesize chitosan derivatives or blending chitosan with other polymers or additives. However, chitosan derivatives found to be less thermal stability than chitosan itself. On the contrary, adding some lipid additive could improve thermal stability of chitosan. In this study, protecting effect of aluminum monostearate (Alst) on thermal stability of chitosan was investigated employing thermal analysis techniques, e.g. thermogravimetry (TG), differential scanning calorimetry (DSC) and hot-stage microscope. Lactic acid solution (2% w/v) was used as solvent for dissolving chitosan. Chitosan solution, named as chtiosan-lactate (CL) and chitosan solution contained 2.5% w/w Alst (CLAlst) were prepared and fabricated into sponges using freeze drying technique. Degradation temperature of CLAlst system investigated from TG was shifted to the higher temperature comparing that of CL which indicated that Alst could improve thermal stability of chitosan after processed as biomaterial. From DSC result, small endothermic peak was observed around 60-70°C for CLAlst whereas that of CL did not exhibit any peak. Melting behavior of the sponges observed under hot-stage microscope was demonstrated that chitosan was decomposed whereas Alst dispersed in chitosan backbone was gradually melted.

Thermal Stability of N-Heterocycle-Stabilized Iodanes – A Systematic Investigation

2019 ◽  
Author(s):  
Andreas Boelke ◽  
Yulia A. Vlasenko ◽  
Mekhman S. Yusubov ◽  
Boris Nachtsheim ◽  
Pavel Postnikov
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Systematic Investigation ◽  
Scanning Calorimetry ◽  
Thermal Stability Of

<p>The thermal stability of pseudocyclic and cyclic <i>N</i>-heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-l<sup>3</sup>-iodanes (NHIs) through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is investigated. NHIs bearing <i>N</i>-heterocycles with a high N/C-ratio such as triazoles show among the lowest descomposition temperatures and the highest decomposition energies. A comparison of NHIs with known (pseudo)cyclic benziodoxolones is made and we further correlated their thermal stability with reactivity in a model oxygenation. </p>

scholarly journals Synthesis and photocatalytic properties of Sn–TiO2 nanomaterials

2020 ◽  
Vol 10 (01n02) ◽  
pp. 2060018
Author(s):  
E. M. Bayan ◽  
T. G. Lupeiko ◽  
L. E. Pustovaya ◽  
M. G. Volkova
Keyword(s):  
Phase Transition ◽  
Thermal Stability ◽  
Sol Gel ◽  
Rutile Phase ◽  
Photocatalytic Properties ◽  
Light Activation ◽  
X Ray ◽  
Tio2 Nanomaterials ◽  
Visible Light Activation ◽  
Thermal Stability Of

Sn-doped TiO2 nanomaterials were synthesized by sol–gel method. It was shown the phase compositions and phase transitions change with the introduction of different tin amounts (0.5–20[Formula: see text]mol.%). X-ray powder diffraction was used to study the effect of different tin amounts on the anatase–rutile phase transition. It was found that the introduction of ions increases the thermal stability of anatase modifications. The material’s photocatalytic activity was studied in reaction with a model pollutant (methylene blue) photodegradation under UV and visible light activation. The best photocatalytic properties were shown for material, which contains 5[Formula: see text]mol.% of Sn.

scholarly journals Isothermal Vulcanization and Non-Isothermal Degradation Kinetics of XNBR/Epoxy/XNBR-g-Halloysite Nanotubes (HNT) Nanocomposites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2872
Author(s):  
Seyed Mohamad Reza Paran ◽  
Ghasem Naderi ◽  
Elnaz Movahedifar ◽  
Maryam Jouyandeh ◽  
Krzysztof Formela ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Degradation Kinetics ◽  
Halloysite Nanotubes ◽  
Butadiene Rubber ◽  
Order Model ◽  
Scanning Calorimetry ◽  
Theoretical Methods ◽  
Vulcanization Kinetics ◽  
Kinetics Of ◽  
Thermal Stability Of

The effect of several concentrations of carboxylated nitrile butadiene rubber (XNBR) functionalized halloysite nanotubes (XHNTs) on the vulcanization and degradation kinetics of XNBR/epoxy compounds were evaluated using experimental and theoretical methods. The isothermal vulcanization kinetics were studied at various temperatures by rheometry and differential scanning calorimetry (DSC). The results obtained indicated that the nth order model could not accurately predict the curing performance. However, the autocatalytic approach can be used to estimate the vulcanization reaction mechanism of XNBR/epoxy/XHNTs nanocomposites. The kinetic parameters related to the degradation of XNBR/epoxy/XHNTs nanocomposites were also assessed using thermogravimetric analysis (TGA). TGA measurements suggested that the grafted nanotubes strongly enhanced the thermal stability of the nanocomposite.

Flammability and Thermal Degradation of Polystyrene/Cadmium Sulfate Nanocomposites

2013 ◽  
Vol 820 ◽  
pp. 84-87
Author(s):  
Zheng Zhou Wang ◽  
Charles A. Wilkie
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Cone Calorimeter ◽  
Cds Nanoparticles ◽  
Solvothermal Process ◽  
Cadmium Sulfate ◽  
Peak Heat Release Rate ◽  
Microscale Combustion Calorimeter ◽  
Combustion Calorimeter ◽  
Thermal Stability Of

Cadmin sulfate nanoparticles, hollow sphere (CdS-HS) and rode (CdS-NR) were synthesized by ultrasonic and solvothermal process, respectively. The effect of the two kinds of nanoparticles on flammability of polystyrene was investigated using cone calorimeter (Cone) and microscale combustion calorimeter (MCC). Cone data indicate that the incorporation of 1% CdS nanoparticles leads to a about 20% reduction in the peak heat release rate (PHRR) compared to the pure PS; CdS-NR is more efficient in reducing the PHRR proved by both Cone and MCC results. The TG results show that the addition of the nanoparticles mainly increases thermal stability of PS at high temepratures.

Grain Growth in Nanocrystalline Nickel

1999 ◽  
Vol 580 ◽  
Author(s):  
G.D. Hibbard ◽  
U. Erb ◽  
K.T. Aust ◽  
G. Palumbo
Keyword(s):  
Thermal Stability ◽  
Grain Size ◽  
Grain Growth ◽  
Size Distributions ◽  
Nanocrystalline Nickel ◽  
Scanning Calorimetry ◽  
Solute Content ◽  
Grain Size Distributions ◽  
Thermal Stability Of ◽  
Total Solute Content

AbstractIn this study, the effect of grain size distribution on the thermal stability of electrodeposited nanocrystalline nickel was investigated by pre-annealing material such that a limited amount of abnormal grain growth was introduced. This work was done in an effort to understand the previously reported, unexpected effect, of increasing thermal stability with decreasing grain size seen in some nanocrystalline systems. Pre-annealing produced a range of grain size distributions in materials with relatively unchanged crystallographic texture and total solute content. Subsequent thermal analysis of the pre-annealed samples by differential scanning calorimetry showed that the activation energy of further grain growth was unchanged from the as-deposited nanocrystalline nickel.

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