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1

Synthesis and Kinetic Study of a PCL-GAP-PCL Tri-block Copolymer

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Chizari M. , Bayat Y.

Central European Journal of Energetic Materials

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2018

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tom Vol. 15, no. 2

243--257

EN

An energetic tri-block copolymer PCL-GAP-PCL (Mn = 1794) was synthesized by a ring-opening polymerization of ε-caprolactone with glycidyl azide polymer (GAP) of low molecular weight (Mn = 1006 g/mol) as initiator, in the presence of dibutyltin dilaurate (DBTDL) as catalyst, at 100 °C in the absence of solvent. The products obtained in high yield were characterized by FTIR, gel permeation chromatography (GPC), and 1H and 13C NMR spectroscopy. Thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) were used to study the thermal behaviour of the polymers. An advanced isoconversional method has been applied for kinetic analysis. The activation energy, calculated by the Flynn-Wall-Ozawa (FWO) and Kissinger methods, and thermal analysis revealed that the tri-block copolymer has greater thermal stability than homopolymer GAP. The results of the activation energies from the Kissinger method for the first and second steps were 180.3 kJ·mol−1 and 209.8 kJ·mol−1, respectively. Furthermore, for the copolymer, the activation energy versus the level of conversion was calculated by the FWO method. The glass transition temperature (Tg) for GAP was influenced by the PCL blocks; as a result the copolymer (Tg = −64 °C) showed better thermal properties than homopolymer GAP (Tg = −48 °C).

2

Improved Synthesis of Glycidyl Nitrate in the Presence of 5-Aminotetrazolium Nitrate: a New Method Optimised Using the Taguchi Method

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Bayat Y. , Mohammadi M. M.

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2016

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tom Vol. 13, no. 3

579--591

EN

This paper describes a method for increasing the yield of glycidyl nitrate from chloro-epoxypropane and dilute nitric acid, in the presence of 5-aminotetrazolium nitrate. The presence of 5-aminotetrazolium nitrate as catalyst and co-nitrating agent, enabled glycidyl nitrate to be produced smoothly and in excellent yield under mild condition. The optimal reaction conditions were obtained by the Taguchi method, increasing the yield from 66 to 81%. The product was characterized by FTIR and 1H NMR spectroscopy.

3

Synthesis of Novel Energetic N-(1-Carboxymethyl-1H-tetrazole-5-yl)-hydrazinium Salts

100%

Bayat Y. , Taheripouya G.

Central European Journal of Energetic Materials

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2018

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tom Vol. 15, no. 3

420--434

EN

Synthesis of materials with acceptable performance and low sensitivity to physical stimuli is one of the overall goals of energetic materials. The creation of networks of hydrogen bonds affords good stability to the trigger bonds. In this respect azole-based ionic high-energy materials (especially aminotetrazoles) and other nitrogen-rich compounds have strong hydrogen bonds. Significant stability, insensitivity to a physical stimulus and also good performance are thus created. In this study salts derived from N-(1-carboxymethyl-1H-tetrazole-5-yl)-hydrazinium chloride were synthesized. Anion exchange of the chlorine with nitrate, 5-aminotetrazolate, (5-amino-tetrazole-1-yl)-acetate and (5-nitriminotetrazole-1-yl)-acetate was performed, with precipitation of AgCl. All of the products were characterized using 1H NMR, 13C NMR, FTIR spectroscopy, differential scanning calorimetry (DSC), impact sensitivity and UV-Vis spectroscopy. Among the advantages of this study are the use of methods and available equipment and low-risk solvents during the reaction and the formation of minimum by-products.

4

Statistical Optimization of the Preparation of HNIW Nanoparticles via Oil in Water Microemulsions

80%

Bayat Y. , Zarandi M. , Khadiv-Parsi P. , Salimi Beni A.

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tom Vol. 12, no. 3

459--472

EN

HNIW (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) is a family member of high-energy density cage nitramines which have so many versatile applications. In this paper, HNIW nanoparticles were prepared by the oil in water microemulsion route. The effects of various experimental parameters on this reaction were investigated using the Taguchi method. The effects of different variables: organic phase, water/organic phase (W1/W2), organic phase/ propanol (W3/W4) and HNIW weight percent, on the particle size of the HNIW were investigated at three distinct levels. Optimal conditions for obtaining HNIW nanoparticles were determined. Performing the process under the optimal conditions proposed by the Taguchi method leads to the production of HNIW nanoparticles with an average size of about 80 nm. The HNIW nanoparticles were characterized using Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), Differential Thermal Analysis (DTA) and X-Ray Diffraction (XRD).

5

Reductive Debenzylation of Hexabenzylhexaazaisowurtzitane using Multi-walled Carbon Nanotube-supported Palladium Catalysts: an Optimization Approach

80%

Bayat Y. , Malmir S. , Hajighasemali F. , Dehghani H.

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tom Vol. 12, no. 3

439--458

EN

This study focuses on the optimization of parameters affecting the reductive debenzylation of hexabenzylhexaazaisowurtzitane using multiwalled carbon nanotube-supported palladium catalysts. Initially the influence of functionalized carbon nanotubes, including OH and COOH groups, were compared with basic multi-walled carbon nanotubes, and their impact on the reaction yield was evaluated. Among these catalyst supports, hydroxylated multi-walled carbon nanotubes showed superior efficiency for producing tetraacetyldibenzylhexaazaisowurtzitane from hexabenzylhexaazaisowurtzitane. The effect of catalyst preparation factors on the reaction yield were screened by using a 25-2 fractional factorial design. Parameters, including percent palladium, adsorption time, pH and adsorption temperature, were optimized by applying a central composite design. The optimum values of these factors were: 12.97% Pd, adsorption time 1.81 h, pH 9.61 and adsorption temperature 42.78 °C. A value of 76% was obtained for the reaction yield under optimum conditions.