scholarly journals Hydrogen desorption from nanostructured magnesium hydride composites

2007 ◽  
Vol 61 (2) ◽  
pp. 71-74
Author(s):  
Tanja Brdaric ◽  
Ljiljana Stamenkovic ◽  
Nikola Novakovic ◽  
Jasmina Grbovic-Novakovic
Keyword(s):  
Hydrogen Desorption ◽  
Morphological Characterization ◽  
Magnesium Hydride ◽  
Sem Analysis ◽  
Main Role ◽  
Desorption Peak ◽  
Additive Particles ◽  
Metal Addition ◽  
Thermal Stability Of ◽  
Metal Additive

The influence of 3d transition metal addition (Fe, Co and Ni) on the desorption properties of magnesium hydride were studied. The ball milling of MgH2-3d metal blends was performed under Ar. Microstructural and morphological characterization were performed by XRD and SEM analysis, while the hydrogen desorption properties were investigated by DSC. The results show a strong correlation between the morphology and thermal stability of the composites. The complex desorption behavior (the existence of more than one desorption peak) was correlated with the dispersion of the metal additive particles that appear to play the main role in the desorption. The desorption temperature can be reduced by more than 100 degrees if Fe is added as additive. The activation energy for H2 desorption from the MgH2-Fe composite is 120 kJ/mol, implying that diffusion controls the dehydration process.

scholarly journals Catalitic effect of Co on hydrogen desorption form nanostucturated magnesium hydride

2008 ◽  
Vol 62 (3) ◽  
pp. 114-118
Author(s):  
Ljiljana Matovic ◽  
Snezana Milovanovic ◽  
Milica Drvendzija ◽  
Jasmina Grbovic-Novakovic
Keyword(s):  
Hydrogen Desorption ◽  
Morphological Characterization ◽  
Nucleation And Growth ◽  
Desorption Kinetics ◽  
Dehydration Process ◽  
Additive Particles ◽  
Metal Addition ◽  
Kinetics Of ◽  
New Phase ◽  
Metal Additive

To study the influence of 3d transition metal addition on desorption kinetics of MgH2 ball milling of MgH2-Co blends was performed under Ar. Microstructural and morphological characterization, performed by XRD and SEM, show a huge correlation with thermal stability and hydrogen desorption properties investigated by DSC. A complex desorption behavior is correlated with the dispersion of the metal additive particles on hydride matrix. The activation energy for H2 desorption from MgH2-Co composite was calculated from both non-isothermal and isothermal methods to be 130 kJ/mol which means that mutually diffusion and nucleation and growth of new phase control the dehydration process.

Desorption Behaviour in Nanostructured MgH2-Co

2006 ◽  
Vol 518 ◽  
pp. 79-84 ◽  
Author(s):  
Amelia Montone ◽  
Jasna Grbović Novaković ◽  
Lj. Stamenković ◽  
Luca Pasquini ◽  
Anna Lisa Fiorini ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Ball Milling ◽  
Catalyst Concentration ◽  
Hydrogen Desorption ◽  
Morphological Characterization ◽  
Main Role ◽  
Synthesis Route ◽  
Co Addition ◽  
Catalytic Particles

The influence of the Co addition and synthesis route on desorption properties of MgH2 were investigated. Ball milling of MgH2-Co blends was performed under Ar using different milling intensities and different weight ratios. Microstructural and morphological characterization, performed by XRD and SEM, show a huge correlation with thermal stability and hydrogen desorption properties investigated by DSC. A complex desorption behaviour is correlated with the dispersion of the catalytic particles that appears to play a main role in desorption performances. The optimum catalyst concentration was found to be around 10 wt.%, while the optimum value of the ball to powder ratio was 10:1.

scholarly journals Development of Nervilia fordii Extract-Loaded Electrospun PVA/PVP Nanocomposite for Antioxidant Packaging

Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1728
Author(s):  
Peng Wen ◽  
Teng-Gen Hu ◽  
Yan Wen ◽  
Ke-Er Li ◽  
Wei-Peng Qiu ◽  
...  
Keyword(s):  
Food Packaging ◽  
Thermo Gravimetric Analysis ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Poly Vinyl Alcohol ◽  
Total Phenolic ◽  
Gravimetric Analysis ◽  
Thermo Gravimetric ◽  
Phenolic And Flavonoid ◽  
Thermal Stability Of

An ethyl acetate extract from of Nervilia fordii (NFE) with considerable suppression activity on lipid peroxidation (LPO) was first obtained with total phenolic and flavonoid contents and anti-LPO activity (IC50) of 86.67 ± 2.5 mg GAE/g sample, 334.56 ± 4.7 mg RE/g extract and 0.307 mg/mL, respectively. In order to improve its stability and expand its application in antioxidant packaging, the nano-encapsulation of NFE within poly(vinyl alcohol) (PVA) and polyvinyl(pyrrolidone) (PVP) bio-composite film was then successfully developed using electrospinning. SEM analysis revealed that the NFE-loaded fibers exhibited similar morphology to the neat PVA/PVP fibers with a bead-free and smooth morphology. The encapsulation efficiency of NFE was higher than 90% and the encapsulated NFE still retained its antioxidant capacity. Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD) analysis confirmed the successful encapsulation of NFE into fibers and their compatibility, and the thermal stability of which was also improved due to the intermolecular interaction demonstrated by thermo gravimetric analysis (TGA). The ability to preserve the fish oil’s oxidation and extend its shelf-life was also demonstrated, suggesting the obtained PVA/PVP/NFE fiber mat has the potential as a promising antioxidant food packaging material.

The influence of thickness of CrN coating on the durability of hot forging dies

2011 ◽  
Vol 1 (2) ◽  
Author(s):  
Jerzy Smolik
Keyword(s):  
Coating Thickness ◽  
Nitrided Layer ◽  
Hot Forging ◽  
Sem Analysis ◽  
Internal Stresses ◽  
Main Role ◽  
Hybrid Layer ◽  
Crn Coating ◽  
Forging Process

AbstractThis article presents results which enabled the determination of the role of CrN coating and the influence of its thickness on the effectiveness of hybrid layer “nitrided layer / CrN coating” in the process of increasing the durability of forging dies. Dies coated with hybrid layers “nitrided layer / CrN coating” with various CrN coating thickness were — after different maintenance periods — subjected to metallographic testing, 3D shape testing and SEM analysis. Hardness distribution was also determined. The obtained results revealed that for all tested dies, independently from CrN coating thickness, the main mechanisms of their destruction was mechanical and thermal fatigue, and plastic deformation. It has been shown that the main role of CrN coating in the hybrid layer ”nitrided layer / PVD coating” is to counteract a high temperature influence the source of which is forging on die material. In order to do so the CrN coating should be characterized by a considerably lower thermal conductivity coefficient to steel and low hardness so that it can efficiently resist fatigue processes in the forging process. Based on testing conducted by means of the sin 2 φ method, it was revealed that internal stresses are vitally important for CrN coating for fatigue resistance of hybrid layer ”nitrided layer / CrN coating” during the forging process.

Reaction pathways for hydrogen desorption from magnesium hydride/hydroxide composites: bulk and interface effects

2010 ◽  
Vol 12 (3) ◽  
pp. 572-577 ◽  
Author(s):  
F. Leardini ◽  
J. R. Ares ◽  
J. Bodega ◽  
J. F. Fernández ◽  
I. J. Ferrer ◽  
...  
Keyword(s):  
Hydrogen Desorption ◽  
Magnesium Hydride ◽  
Reaction Pathways ◽  
Interface Effects

Preparation of Poly(aniline-co-phenol) and Study Its Properties and Its Polymerization Kinetics Using Two Methods: UV-Vis and HPLC

2021 ◽  
Vol 43 (5) ◽  
pp. 505-505
Author(s):  
Juhaina Alghdir and Ahmad Falah Juhaina Alghdir and Ahmad Falah
Keyword(s):  
Transition Temperature ◽  
Reaction Order ◽  
Sem Analysis ◽  
304 Stainless Steel ◽  
Melting Transition ◽  
Gravimetric Analysis ◽  
Zero Order Reaction ◽  
Kinetics Of ◽  
Thermal Stability Of ◽  
Poly Aniline

The co-polymerization of polyaniline is one of the most important methods used to improve the electrical activity and thermal stability of polyaniline. Previously, electrochemical co-polymerization of phenol and aniline was performed on 304 stainless steel anodes. In this study, we present the co-polymerization of aniline and phenol chemically at laboratory temperature in an acidic medium with ammonium pyrosulfate as an oxidant. The Scanning Electron Microscopy (SEM) analysis of poly(aniline-co-phenol) sample shows a rough (non-smooth) surface with crystalline particles with microscopic diameters. We characterized the prepared polymer with DSC, DTA, and thermos gravimetric analysis (TGA). We found that the thermal decomposition of poly(aniline-co-phenol) was on six steps. The glass transition temperature of the co-polymer (Tg) was found at 863.89 and#176;C and the melting transition temperature was observed at 877.80 and#176;C. We studied the kinetics of Poly(aniline-co-phenol) using two methods: UV-Vis, HPLC. Then we determined the reaction order. It was found that the reaction was the zero-order reaction (n=0) in both previous two methods.

Influence of VO2 nanostructured ceramics on hydrogen desorption properties from magnesium hydride

2013 ◽  
Vol 39 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Sanja Milošević ◽  
Željka Rašković-Lovre ◽  
Sandra Kurko ◽  
Radojka Vujasin ◽  
Nikola Cvjetićanin ◽  
...  
Keyword(s):  
Hydrogen Desorption ◽  
Magnesium Hydride ◽  
Nanostructured Ceramics

Hydrogen desorption properties of magnesium hydride catalyzed multiply with carbon and silicon

2015 ◽  
Vol 645 ◽  
pp. S80-S83 ◽  
Author(s):  
Alicja Klimkowicz ◽  
Akito Takasaki ◽  
Łukasz Gondek ◽  
Henryk Figiel ◽  
Konrad Świerczek
Keyword(s):  
Hydrogen Desorption ◽  
Magnesium Hydride

scholarly journals A Morphological Characterization of High Yield Chitin from Periwinkle Shells

2020 ◽  
Vol 5 (4) ◽  
pp. 61-65
Author(s):  
Cletus Chiosa Odili ◽  
Oluwashina Philips Gbenebor ◽  
Henry Adekola Haffner ◽  
Samson Oluropo Adeosun
Keyword(s):  
Mechanical Properties ◽  
Crystal Size ◽  
Complete Removal ◽  
Morphological Characterization ◽  
Sem Analysis ◽  
High Yield ◽  
Xrd Patterns ◽  
Analytical Tools ◽  
Periwinkle Shell

Research on obtaining chitin from periwinkle shell is scarce due to the very low yield of chitin from this kind of shell. Thisstudy reports a method of processing periwinkle shells to obtain high yield, bio-medically suitable chitin. The experimentwas designed using IM and 2M concentrations of HCl for demineralization and a 1M NaOH concentration for deproteinization. FTIR, SEM, XRD and DTA analytical tools were used to characterize the extracted chitin. The FTIR spectral, XRD patterns and SEM analysis, revealed the complete removal of calcium carbonate by the acid concentrations used. The particle-like form of periwinkle shell was transformed to sheet-like fiber and globular-like fiber of α-chitin by increasing the concentration of HCl from1M to 2M respectively. The crystal size increased from 11.2Å (1M HCl) to 13.4Å (2M HCl). The yield of chitin from periwinkle shell also increased from 52% to 71% using 1M and 2M HCl respectively. Thus, acid concentrations can be used to alter the structure of chitin with different mechanical properties.

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