scholarly journals Preparation and Characterization of Spherical Submicron CL-20 by Siphon Spray Refinement

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Jiangtao Xing ◽  
Weili Wang ◽  
Wenzheng Xu ◽  
Tianle Yao ◽  
Jun Dong ◽  
...  
Keyword(s):  
Impact Sensitivity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Crystal Forms ◽  
Refined Method ◽  
Diffraction Angle ◽  
Ultrasonic Assisted ◽  
The Impact ◽  
Thermal Stability Of

In order to improve the safety of hexanitrohexaazaisowurtzitane (CL-20), submicron CL-20 particles were prepared by a siphon ultrasonic-assisted spray refining experimental device. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC), and the impact sensitivity of the samples was tested. The results show that the particle size of siphon-refined CL-20 is about 800 nm~1 μm, which is more smooth, mellow, and dense than that of CL-20 prepared by a traditional pressure-refined method. The peak diffraction angle of pressure- and siphon-refined CL-20 is basically the same as that of raw CL-20, and their crystal forms are ε type. The peak strength of pressure- and siphon-refined CL-20 decreased obviously. The apparent activation energy of pressure-refined CL-20 and siphon-refined CL-20 is 13.3 kJ/mol and 11.95 kJ/mol higher than that of raw CL-20, respectively. The thermal stability of CL-20 is improved. The activation enthalpy (ΔH#) is significantly higher than that of raw CL-20, and the characteristic drop is 70.4% and 82.7% higher than that of raw CL-20. The impact sensitivity of siphon-refined CL-20 is lower than that of pressure-refined CL-20, so the safety performance of an explosive is improved obviously.

scholarly journals Characterization of the Interface Between the Bulk Glass Forming Alloy Zr41Ti14Cu12Ni10Be23 with Pure Metals and Ceramics

2000 ◽  
Vol 15 (7) ◽  
pp. 1617-1621 ◽  
Author(s):  
Jan Schroers ◽  
Konrad Samwer ◽  
Frigyes Szuecs ◽  
William L. Johnson
Keyword(s):  
Sessile Drop ◽  
Bulk Glass ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Glass Forming ◽  
Processing Times ◽  
Thermal Stability Of

The reaction of the bulk glass forming alloy Zr41Ti14Cu12Ni10Be23 (Vit 1) with W, Ta, Mo, AlN, Al2O3, Si, graphite, and amorphous carbon was investigated. Vit 1 samples were melted and subsequently solidified after different processing times on discs of the different materials. Sessile drop examinations of the macroscopic wetting of Vit 1 on the discs as a function of temperature were carried out in situ with a digital optical camera. The reactions at the interfaces between the Vit 1 sample and the different disc materials were investigated with an electron microprobe. The structure and thermal stability of the processed Vit 1 samples were examined by x-ray diffraction and differential scanning calorimetry. The results are discussed in terms of possible applications for composite materials.

Preparation by solution mixing and characterization of condensation type poly(dimethyl siloxane)/graphene nanoplatelets composites

2021 ◽  
pp. 002199832110558
Author(s):  
Panayiotis Ketikis ◽  
Efthimios Damopoulos ◽  
Georgios Pilatos ◽  
Panagiotis Klonos ◽  
Apostolos Kyritsis ◽  
...  
Keyword(s):  
Graphene Nanoplatelets ◽  
Matrix Composites ◽  
Dielectric Relaxation Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Melting Temperatures ◽  
Dimethyl Siloxane ◽  
Diffraction Patterns ◽  
The Impact

The impact of the incorporation of graphene nanoplatelets (GN) on the properties of hydroxyl-terminated poly(dimethylsiloxane) (PDMS) matrices was investigated. The composites were prepared by solution mixing, using tetrahydrofuran (THF) as a solvent. Brookfield viscosimetry, implemented during the vulcanization process, revealed that GN increases the viscosity of the system, compared to pristine PDMS, proportionally to its concentration. X-ray diffraction patterns suggested an efficient dispersion of GN in the polysiloxane matrix. The D and G bands ratio (ID/IG) calculation, based on RAMAN spectra of GN/PDMS specimens, revealed more defects in graphene nanoplatelets when incorporated in the PDMS matrix. By differential scanning calorimetry (DSC), a marginal increase in crystallization, glass transition and melting temperatures of PDMS in GN/PDMS composites was observed. Improvement of the thermal stability of LMW PDMS composites, especially for higher GN concentrations (3 and 5 phr), was noticed by thermogravimetric analysis (TGA). Additionally, GN enhanced the tensile strength of composites, up to 73% for the 3 phr GN/LMW PDMS composite. A significant increase in the elongation at break was recorded, whereas no effect on the modulus of elasticity was recorded. The decrease in toluene-swelling, for the LMW PDMS matrix composites, was attributed to the increase in the tortuosity path because of the efficient dispersion of GN. A decrease in oxygen permeability of 55–65% and 44–58% was measured in membranes made of PDMS composites containing 0.5 phr and 1 phr GN, respectively. Dielectric relaxation spectroscopy (DRS) measurements recorded a significant increase in the conductivity of the higher graphene content composites.

scholarly journals Synthesis and characterization of allyl- and vinyl-substituted 1,2-bis(tetrazolo)ethanes as polymeric precursors

2016 ◽  
Vol 71 (12) ◽  
pp. 1199-1209
Author(s):  
Vera A. Hartdegen ◽  
Maximilian S. Hofmayer ◽  
Konstantin Karaghiosoff ◽  
Thomas M. Klapötke
Keyword(s):  
Allyl Bromide ◽  
2D Nmr ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
2D Nmr Spectroscopy ◽  
X Ray ◽  
Physical Stimuli ◽  
Thermal Stability Of

AbstractOn the basis of 1,2-bis(5-tetrazolo)ethane (BTE) the corresponding twofold vinyl and allyl N-substituted derivatives were synthesized using 1,2-dibromoethane and allyl bromide, respectively. The compounds were obtained as two different constitutional isomers. Both species were analyzed using NMR and IR spectroscopy, elemental analysis, as well as mass spectrometry. In the case of the diallyl bistetrazoles, the two isomers were characterized using 2D NMR spectroscopy. The synthesis of the divinyl compounds gave crystals of the 2,2′-N-substituted isomer, which were analyzed by single-crystal X-ray diffraction. The thermal stability of the compounds was determined using differential scanning calorimetry (DSC) and gave decomposition temperatures around 190°C and 230°C. For the investigation of the inherent energetic potential, sensitivities toward physical stimuli and detonation parameters were determined. The compounds turned out to be insensitive toward friction and impact and possess moderate energetic properties.

Preparation and Characterization of Polypropylene/Clay Nanocomposites

2011 ◽  
Vol 55-57 ◽  
pp. 1584-1587 ◽  
Author(s):  
Li Mei Wang
Keyword(s):  
Xrd Analysis ◽  
Decomposition Temperature ◽  
Clay Nanocomposites ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Xrd Pattern ◽  
Solution Blending ◽  
Clay Layers ◽  
Thermal Stability Of

Polypropylene(PP)/clay nanocomposites were prepared by solution blending. The microstructure of PP/clay nanocomposites was studied by wide-angle X-ray diffraction (XRD) analysis. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to investigate thermal properties of PP/clay nanocomposites. XRD pattern prove that clay layers were exfoliated into nanometer size in PP matrix and that α-Phase crystallite was the main crystallite of PP in PP/clay nanocomposites. TGA examinations confirmed that the maximum decomposition temperature of PP/clay nanocomposites was higher than that of neat PP and that the thermal stability of PP/clay nanocomposites rose noticeably. Results of DSC scans showed the crystalliztion temperature of nanocomposites was slightly bigger than that of pure PP due to the efficient nucleating effects of clay layers.

Preparation and Properties of Organo-Montmorillonite Modified R-122 Nanocomposite

2012 ◽  
Vol 602-604 ◽  
pp. 254-258
Author(s):  
Chun Qing Huo ◽  
Hong Juan Gu ◽  
Zai Qian Yu ◽  
Long Zhang
Keyword(s):  
High Performance ◽  
Cetyl Trimethyl Ammonium Bromide ◽  
Ammonium Bromide ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Organic Montmorillonite ◽  
Ft Ir ◽  
Cetyl Trimethyl Ammonium ◽  
The Impact ◽  
Thermal Stability Of

An OMMT (organic montmorillonite) was prepared by ion exchanging between Na-montmorillonite and cetyl trimethyl ammonium bromide (CTAB) and was applied to modify Dicyclopentadiene Dioxide Epoxy(R-122). FT-IR spectra showed that the organic molecules had intercalated into the layers of MMT successfully, X-ray diffraction illustrated that the spacing of layers of MMT increased from 1.43 nm to 3.85 nm. R-122 composite was prepared with this nano-organic montmorillonite. When the content of OMMT was 4.0% (wt%), the impact strenth of the composite reached to the highest(21.2 J/m), which is 92.7% higher than the pure R-122 . Morphology of the fracture checked by SEM, reveals a depth depended distribution which generated more new surface, thus can absorb more impact energy. Differential scanning calorimetry(DSC) showed that the thermal stability of the composite had improved compared with the pure resin. And what’s more, the improvement of toughness doesn’t hurt the resin’s heat resistance, it may provid a new way to prepare high performance R-122 composites.

Preparation and characterization of poly(3-hydroxybutyrate)/ Cloisite25A nanocomposites

e-Polymers ◽  
2013 ◽  
Vol 13 (1) ◽  
Author(s):  
Matko Erceg ◽  
Dražan Jozić
Keyword(s):  
Crystallization Rate ◽  
Nucleating Agent ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Tg Analysis ◽  
Solution Intercalation ◽  
X Ray ◽  
Thermal Stability Of

Abstract Poly(3-hydroxybutyrate)/Cloisite25A (PHB/25A) nanocomposites were prepared by solution-intercalation method. The intercalation of PHB chains between the layers of Cloisite25A was observed by X-ray diffraction (XRD). Differential scanning calorimetry (DSC) and non-isothermal thermogravimetry (TG) analysis were performed to study the thermal properties, crystallization and the thermal degradation of the prepared nanocomposites. DSC analysis indicates that Cloisite25A acts as a nucleating agent and increases the crystallization rate of PHB, but due to intercalation reduces its overall degree of crystallinity. TG analysis shows that addition of Cloisite25A enhances the thermal stability of PHB.

Structure and Properties of Silk Grafted with 2-Hydroxyethyl Methacrylate by ARGET ATRP

2012 ◽  
Vol 441 ◽  
pp. 332-336
Author(s):  
Jie Liu ◽  
Shi Wei Li ◽  
Xia Xu ◽  
Tie Ling Xing ◽  
Guo Qiang Chen
Keyword(s):  
Control Sample ◽  
Hydroxyethyl Methacrylate ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Arget Atrp ◽  
Ft Ir ◽  
Recovery Angle ◽  
Dsc Curves ◽  
Thermal Stability Of

In this work, silk was reacted with 2-bromoisobutyryl bromide to obtain silk macroinitiator for activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP). Silk macroinitiator was grafted with 2-hydroxyethyl methacrylate (HEMA) via ARGET ATRP method to produce grafted silk in water aqueous. FT-IR characterization of the modified silk substrate showed that HEMA had been grafted onto the silk surface. Scanning electron microscopy (SEM) photos of the grafted silks showed significant differences from the untreated silk. X-ray diffraction curves demonstrated that the crystalline structure of silk remained unchanged regardless of the HEMA grafting. Differential scanning calorimetry (DSC) curves indicated that the thermal stability of the grafted silk was improved. The whiteness, strength and moisture regain of the grafted silk decreased slightly, but the wrinkle recovery angle of the grafted silk increased distinctly compared with the control sample.

scholarly journals Synthesis and characterization of dextran ester derivatives and their adhesive properties

2019 ◽  
Vol 65 (1) ◽  
Author(s):  
Azusa Togo ◽  
Yukiko Enomoto ◽  
Akio Takemura ◽  
Tadahisa Iwata
Keyword(s):  
Breaking Strength ◽  
Value Added ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Adhesive Properties ◽  
X Ray ◽  
Practical Applications ◽  
Hot Melt ◽  
Thermal Stability Of

AbstractPolysaccharides are promising renewable alternatives to petroleum-based plastics, and are high-value-added materials in various industries. In this work, we synthesized dextran (α-1,6-glucan) ester derivatives substituting acyl groups with different carbon numbers from acetate to laurate. We found that the thermal stability of dextran was improved by esterification. Moreover, using differential scanning calorimetry and X-ray diffraction, we revealed that dextran ester derivatives were amorphous. Self-standing, transparent, solvent-cast films of dextran ester derivatives were prepared. Dextran ester derivatives adhered to various materials, including polyvinyl alcohol (PVA) films, wood, glass, and aluminum. In addition, the adhesive interfaces were transparent, which is important for practical applications. The adhesive strength for PVA films increased with concentration, exceeding the breaking strength of the PVA film at 0.3 g/mL. Moreover, dextran valerate and dextran hexanoate behaved as hot-melt-type adhesives. These results demonstrate the potential of dextran ester derivatives as biomass-based adhesives.

Glibenclamide-Nicotinamide Cocrystals Synthesized by The Solvent Evaporation Method to Enhance Solubility and Dissolution Rate of Glibenclamide

2019 ◽  
Vol 9 (01) ◽  
pp. 21-26
Author(s):  
Arif Budiman ◽  
Ayu Apriliani ◽  
Tazyinul Qoriah ◽  
Sandra Megantara
Keyword(s):  
Solvent Evaporation ◽  
Physical Mixture ◽  
Dissolution Profile ◽  
Solvent Evaporation Method ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Evaporation Method ◽  
Dissolution Properties ◽  
Mixture Characterization

Purpose: To develop glibenclamide-nicotinamide cocrystals with the solvent evaporation method and evaluate their solubility and dissolution properties. Methods: Cocrystals of glibenclamide-nicotinamide (1:2) were prepared with the solvent evaporation method. The prediction of interactive cocrystals was observed using in silico method. The solubility and dissolution were performed as evaluation of cocrystals. The cocrystals also were characterized by differential scanning calorimetry (DSC), infrared spectrophotometry, and powder X-ray diffraction (PXRD). Result: The solubility and dissolution profile of glibenclamide-nicotinamide cocrystal (1:2) increased significantly compared to pure glibenclamide as well as its physical mixture. Characterization of cocrystal glibenclamide-nicotinamide (1:2) including infrared Fourier transform, DSC, and PXRD, indicated the formation of a new solid crystal phase differing from glibenclamide and nicotinamide. Conclusion: The confirmation of cocrystal glibenclamide-nicotinamide (1:2) indicated the formation of new solid crystalline phases that differ from pure glibenclamide and its physical mixture

Studies on the Preparation, Characterization and Solubility of -Cyclodextrin-Roxythromycin Inclusion Complexes

2009 ◽  
Vol 2 (2) ◽  
pp. 523-530
Author(s):  
D. Nagasamy Venkatesh ◽  
S. Karthick ◽  
M. Umesh ◽  
G. Vivek ◽  
R.M. Valliappan ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Inclusion Complexes ◽  
Phase Solubility ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Ir Studies ◽  
Poorly Soluble ◽  
Poorly Soluble Drug

Roxythromycin/ β-cyclodextrin (Roxy/ β-CD) dispersions were prepared with a view to study the influence of β-CD on the solubility and dissolution rate of this poorly soluble drug. Phase-solubility profile indicated that the solubility of roxythromycin was significantly increased in the presence of β-cyclodextrin and was classified as AL-type, indicating the 1:1 stoichiometric inclusion complexes. Physical characterization of the prepared systems was carried out by differential scanning calorimetry (DSC), X-ray diffraction studies (XRD) and IR studies. Solid state characterization of the drug β-CD binary system using XRD, FTIR and DSC revealed distinct loss of drug crystallinity in the formulation, ostensibly accounting for enhancement of dissolution rate.

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