Salim Chelouche - Academia.edu (original) (raw)

Papers by Salim Chelouche

ChemistrySelect, Dec 23, 2021

In the present study, the effect of moisture and thermal aging on the degradation of a pyrotechni... more In the present study, the effect of moisture and thermal aging on the degradation of a pyrotechnic igniter composition (PIC) composed of magnesium (Mg) as fuel and dual‐oxidizer of barium nitrate (Ba(NO3)2) and barium peroxide (BaO2) has been investigated to well understand the main compositional and structural changes that may occur. The unaged and aged samples were examined through non‐destructive techniques, namely, Raman and Fourier transform infrared (FTIR) spectroscopies, scanning electron microscopy (SEM), and X‐ray diffraction (XRD). The thermal decomposition behavior and the kinetic parameters of the different Mg‐PIC samples were determined using thermogravimetry (TGA) analysis coupled with a deconvolution approach. The obtained results revealed that the aging processes performed at 65 °C and 85 % relative humidity (RH), respectively, affected the chemical structure of the samples, and the degradation became more pronounced with the increase of the aging time. These changes are attributed to the partial decomposition of barium nitrate, barium peroxide, and the oxidation of magnesium, which generated Ba(NO2)2, MgO, and Mg(OH)2 as degradation products. On the other hand, based on the TGA data, the kinetic modelling was carried out through the deconvolution approach combined with isoconversional kinetic analysis to determine the multiple‐step kinetic behaviors of the different PIC samples. The results revealed that the aging processes may engender various degradation reactions with different activation energies compared to the fresh sample, what can lead to severe changes in stability and untrustworthy performance of the pyrotechnic compositions.

Chemical Engineering Journal, Feb 1, 2023

Combustion Science and Technology, Nov 16, 2022

Journal of Energetic Materials, Sep 9, 2019

Organic eutectics, as well as aniline-based compounds, were recently found to be efficient stabil... more Organic eutectics, as well as aniline-based compounds, were recently found to be efficient stabilizers for solid propellants. In the current work, compatibility of nitrocellulose (NC) with the conventional stabilizer (Diphenylamine (DPA)), one aniline-based compound (N-(2-ethanol)-p-nitroaniline (ENA)), and their eutectic composition (Diphenylamine + N-(2-ethanol)-p-nitroaniline) have been investigated by thermal techniques according to wellknown standards. The compatibility and thermal stability of NC mixtures were further explored using stability tests, kinetic modeling via different isoconversional methods, and the determination of the isokinetic temperature. DPA was found to be highly compatible with NC, whereas compatibility issues appeared once ENA, as well as the eutectic (DPA+ENA), are present in the NC mixture. Moreover, the obtained results suggest an incompatibility between the stabilizers (ENA and DPA) in the eutectic mixture. Finally, it was found that the thermal stability of the NC-based energetic materials was adversely affected if a compatibility problem is observed between the stabilizers and nitrocellulose.

New Journal of Chemistry, 2021

Renewable giant reed has been explored for the first time to develop new advanced high-energy den... more Renewable giant reed has been explored for the first time to develop new advanced high-energy dense biopolymers through carbamate surface functionalization and nitration of native cellulose and cellulose microcrystals.

Thermochimica Acta, Mar 1, 2019

Highlights  The FTIR/XRD/DSC analyses confirm the compatibility between NC and stabilizers.  Th... more Highlights  The FTIR/XRD/DSC analyses confirm the compatibility between NC and stabilizers.  The NC stabilized by MENA + DPA releases the lowest volume of NO (B&J test).  The amount of the gas released by NC/eutectic is close to that stabilized by DPA.  The NC stabilized by the eutectic MENA+DPA presents the highest activation energy.  The eutectic MENA+DPA is a new efficient stabilizer for nitrocellulose.

Macromolecular Chemistry and Physics, Oct 21, 2019

In this study, microcrystalline cellulose nitrate (MCCN) as energetic polymer is successfully obt... more In this study, microcrystalline cellulose nitrate (MCCN) as energetic polymer is successfully obtained from Posidonia oceanica brown algae (POBA). Fourier transform infrared spectroscopy (FTIR) results show alterations in the intensities of some absorption bands, suggesting a significant difference in the chemical structure between microcrystalline cellulose and the emergent MCCN samples. X‐ray diffraction (XRD) measurements indicate that MCCNs are more crystalline than conventional nitrocellulose (NC). According to scanning electron microscopy (SEM), both NC and MCCN reveal a compact structure and a rough surface. Differential scanning calorimetry (DSC) displays that the thermal degradation of MCCNs shifts to lower temperatures compared to the respective NCs. Furthermore, in comparison with NC samples, MCCN samples exhibit high density, high nitrogen content, low viscosity‐average molecular weight, and good thermal stability. On the other hand, kinetic modeling based on DSC data is carried out by isoconversional integral methods to determine Arrhenius parameters and the decomposition mechanisms. It is found that MCCNs present lower activation energies than conventional NCs with a decrease of ≈6%. Finally, this work opens a new pathway to prepare MCCN from POBA, and it is expected to have applications in several areas such as propellants, energetic binders, and gas generators.

Thermochimica Acta, Oct 1, 2020

In this work, the stabilizing effect of softwood and hardwood Kraft lignins on nitrocellulose (NC... more In this work, the stabilizing effect of softwood and hardwood Kraft lignins on nitrocellulose (NC) was assessed. Four samples containing 3% of stabilizer were prepared. DSC and FTIR analyses have been used to check the compatibility of the different systems. The effect of these organic compounds on the stability of NC has been investigated using the conventional stability tests (Vacuum Stability Test (VST) and Bergmann-Jung (BJ)) and the kinetic modeling. The obtained results via VST and BJ suggested that the prepared mixtures are stable. Furthermore, Kinetic modeling, performed by isoconversional methods based on DSC data, revealed that the new stabilizers displayed excellent thermal stability. The reactivity between different Kraft lignins and NO x has been well highlighted by means of FTIR and TGA techniques as well, confirming the potential of these environmentally friendly substances as promising stabilizers for NC-based propellants.

Fluid Phase Equilibria, Oct 1, 2019

Four binary mixtures with potential for stabilizing energetic materials have been investigated. T... more Four binary mixtures with potential for stabilizing energetic materials have been investigated. The phase diagrams of N-(2-methoxyethyl)-p-nitroaniline þ diphenylamine, N-(2-methoxyethyl)-p-nitroaniline þ N-(2-acetoxyethyl)-p-nitroaniline, N-(2-methoxyethyl)-p-nitroaniline þ 2-nitrodiphenylamine, and N-(2methoxyethyl)-p-nitroaniline þ 1,3-diethyl-1,3-diphenylurea have been determined by differential scanning calorimetry. All systems display a simple eutectic behavior. Consistency tests have been applied to inspect the quality of the SLE data, showing very satisfactory quality factors. The SLE data have also been correlated by Wilson and NRTL models. The employed equations calculated the equilibrium temperatures with a root mean square deviations varying from 1.37 to 2.29 K. These models have been applied to compute the excess thermodynamic functions as well, giving highly comparable values for a further qualitative and quantitative analysis. The results show a positive deviation from ideality for all the investigated systems due to the dominant effect of the self-association molecules. The XRD studies revealed the existence of weak interactions between the components in the formed eutectics and suggested that they are mechanical systems.

Zeitschrift für anorganische und allgemeine Chemie, Oct 13, 2020

In the present work, a green synthesis of copper oxide nanoparticles (CuO NPs) has been performed... more In the present work, a green synthesis of copper oxide nanoparticles (CuO NPs) has been performed through a precipitation method using three different copper precursors and sylvestrys leaf extract as a capping agent. Morphology and structure of the obtained CuO NPs were confirmed by X-ray diffraction (XRD), ultraviolet-visible (UV/Vis), Fourier transform infrared (FT-IR) and Raman spectroscopy, as well as scanning electron microscopy (SEM). Moreover, their thermal behavior and catalytic performance were studied using thermogravimetry (TG) and differential scanning calorimetry (DSC). Four isoconversional kinetic methods have been applied to the DSC data obtained at different heating rates in order to determine the kinetic

Propellants, Explosives, Pyrotechnics, May 28, 2019

In this paper, the compatibility of nitrocellulose (NC) with some aniline-based stabilizers was s... more In this paper, the compatibility of nitrocellulose (NC) with some aniline-based stabilizers was studied in order to detect any interaction between these materials. Both thermal techniques [differential scanning calorimetry (DSC) and vacuum stability test (VST)], and supplementary nonthermal techniques [Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and densimetry] were used. The thermal and non-thermal measurements showed that NC was highly compatible with N-(2-methoxyethyl)-pnitroaniline (MENA) and diphenylamine (DPA), while a degree of incompatibility is indicated for N-(2-acetoxymethyl)p-nitroaniline (ANA). The compatibility of the different mixtures was further probed by the kinetic investigation, and the activation energy and the pre-exponential factors were computed. A detailed discussion and comparison of the compatibility results from all the methods are made.

Propellants, Explosives, Pyrotechnics, May 9, 2022

This study was devoted to setting up new methodologies for an accurate assessment of both real an... more This study was devoted to setting up new methodologies for an accurate assessment of both real and equivalent in‐service‐times (RIST/EIST) of homogenous solid propellants (HSP) through a combination of principal component analysis (PCA) and Fourier transform infrared (FTIR) spectroscopy. Four double‐base rocket propellants (DBRP) have been artificially aged at T=338.65 K for 4 months with sampling every 20 days. FTIR showed that the homolytic scission of the O‐NO2 bonds and the hydrocarbon chains of the nitrate esters are the main processes occurring during the chemical decomposition. The scatter plot from PCA of FTIR spectra shows that over 93 % of the variance was described by the first principal component. Moreover, the loading plot designated the three characteristic FTIR bands from the nitro (NO2) group as the most influenced by aging. A new PCA/FTIR experimental way was set to accurately assess the RIST of HSPs. The relative deviation associated with the RIST evaluated by the present procedure and those from the PCA/VST experimental way, recently developed, was found to range from 4.0 % to 6.7 %. Subsequently, a PCA/FTIR prediction model of the EIST is established. The predictions present a relative deviation of less than 7.1 % compared to the recent PCA/VST model. The accuracy of the model was further confirmed using similar DBRPs artificially aged for 6, 8, 10, and 12 months. The relative variation between the RIST provided by the PCA/FTIR procedure and the prediction model was found less than 5 %, thus confirming the highest accuracy of such combination.

Journal of Energetic Materials, Nov 14, 2021

Defence Technology, Apr 1, 2021

The assessment of the real in-service-time (RIST) and the equivalent in-service-time (EIST) of do... more The assessment of the real in-service-time (RIST) and the equivalent in-service-time (EIST) of double base rocket propellants (DBRPs) is of utmost importance for the safe storage and use of weapon systems as well as the efficiency of the accelerated aging plans. In this work, four DBRPs with similar chemical composition and different natural aging have been artificially aged at T ¼ 338.65 K for 4 months with sampling every 30 days. The unaged and artificially aged samples have been investigated by vacuum stability test (VST) at five isothermal temperatures (T ¼ 333.15 K, 343.15 K, 353.15 K, 363.15 K, and 373.15 K). The volume of the evolved gases in VST was found to decrease with natural/artificial aging. Furthermore, the VST data were treated and subjected to principal component analysis (PCA). The results showed excellent discrimination of the DBRP samples according to their stability thermal properties. Most of the variance was described by the first principal component (PC1) whose scores were linearly correlated with the natural aging durations when PCA is applied on VST data obtained at T ¼ 363.15 K. In light of the obtained results, a new experimental way for the estimation of the real/equivalent IST was proposed, which takes into account the impact of the natural aging of the sample. The approach predicts successfully the RIST of two similar DBRPs with a relative deviation of less than 2%. At the specific heating temperature T ¼ 338.65 K, the developed model provides more conceivable EIST values, with asymptotic behavior against artificial aging duration evolution, thus overcoming some shortcomings of the common generalized van't Hoff formula (GvH).

International Journal of Biological Macromolecules, Dec 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Nanomaterials, May 18, 2020

In this study, carbon mesospheres (CMS) and iron oxide nanoparticles decorated on carbon mesosphe... more In this study, carbon mesospheres (CMS) and iron oxide nanoparticles decorated on carbon mesospheres (Fe 2 O 3-CMS) were effectively synthesized by a direct and simple hydrothermal approach. α-Fe 2 O 3 nanoparticles have been successfully dispersed in situ on a CMS surface. The nanoparticles obtained have been characterized by employing different analytical techniques encompassing Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The produced carbon mesospheres, mostly spherical in shape, exhibited an average size of 334.5 nm, whereas that of Fe 2 O 3 supported on CMS is at around 80 nm. The catalytic effect of the nanocatalyst on the thermal behavior of cellulose nitrate (NC) was investigated by utilizing differential scanning calorimetry (DSC). The determination of kinetic parameters has been carried out using four isoconversional kinetic methods based on DSC data obtained at various heating rates. It is demonstrated that Fe 2 O 3-CMS have a minor influence on the decomposition temperature of NC, while a noticeable diminution of the activation energy is acquired. In contrast, pure CMS have a slight stabilizing effect with an increase of apparent activation energy. Furthermore, the decomposition reaction mechanism of NC is affected by the introduction of the nano-catalyst. Lastly, we can infer that Fe 2 O 3-CMS may be securely employed as an effective catalyst for the thermal decomposition of NC.

Materials horizons, Dec 17, 2020

Propellants, Explosives, Pyrotechnics, Apr 22, 2020

Stability control and evaluation for Homogeneous Solid Propellant (HSP) are of paramount importan... more Stability control and evaluation for Homogeneous Solid Propellant (HSP) are of paramount importance for securing ammunition storage warehouses and weapon systems. In the current work, a new procedure for the stability control of HSP was established by combining spectral, thermal, and chemometric tools. Analyses were performed on three similar HSPs naturally aged up to 31 years and subjected to artificial aging (during 12 months at 338.65 K with sampling every 2 months). FTIR analysis showed a decrease in the intensities of the characteristic bands with natural/ artificial aging progress. Vacuum Stability Test (VST) experiments carried out at five isothermal temperatures (333.15 K, 343.15 K, 353.15 K, 363.15 K, and 373.15 K) highlighted three degradation stages during HSP aging. Two kinetic approaches, viz, model-fitting and model-free have been applied to VST data in order to evaluate the kinetic parameters. The activation energy for the HSP degradation reaction was found to decrease with natural/artificial aging progress. Furthermore, the application of the Principal Component Analysis (PCA) to FTIR spectra allows classifying efficiently the samples according to their stability properties. Moreover, the loading plots pointed out the most influenced bands by aging processes. A model, which connected the mean intensity of these bands to the activation energy of the sample, was established. Furthermore, the limit of propellant stability was estimated based on the prediction of the storage lifetimes. The relative error on the activation energy associated with the obtained model was found to be less than 2 % during natural aging up to 20 years and 6 % during artificial aging up to 12 months.

International Journal of Thermophysics, Oct 1, 2018

Differential scanning calorimetry (DSC) is used to investigate the thermal properties of N-(2-eth... more Differential scanning calorimetry (DSC) is used to investigate the thermal properties of N-(2-ethanol)-p-nitroaniline + N-(2-acetoxyethyl)-p-nitroaniline, and their binary systems. The experimental results demonstrate that the studied binary system presents a simple eutectic behavior and the corresponding mole fraction (x eu) of N-(2-ethanol)p-nitroaniline at the eutectic point is 0.5486, whereas the temperature (T eu) is found to be equal to 363.6 K. The quality of the solid-liquid equilibria (SLE) data has been checked by thermodynamic consistency tests, presenting good quality factor. The SLE data have been correlated by means of Wilson, NRTL, and UNIQUAC equations. The three models describe satisfactorily the phase diagram as the root-mean-square deviations for the equilibrium temperatures vary from 1.25 K to 2.07 K. Nevertheless, the Wilson model provides the best correlation results. The three equations have also been used to compute excess thermodynamic functions viz. excess Gibbs energy, enthalpy and entropy. The obtained results revealed a sensitive positive deviation to ideality thus demonstrating the nature of the interactions between the compounds forming the mixture. Microstructural studies have been carried out by FTIR, XRD and optical microscopy showing weak molecular interactions for the eutectic mixture.

Thermochimica Acta, Apr 1, 2020

Abstract In this study, α-Fe2O3 nanoparticles were successfully prepared by a simple and direct h... more Abstract In this study, α-Fe2O3 nanoparticles were successfully prepared by a simple and direct hydrothermal method using three different precursors (iron chloride, iron nitrate and iron sulphate). Structure and morphological characterization of the different nanoparticles have been investigated in detail by using a series of analytical methods including FTIR, Raman, XRD and SEM. The synthesized nanoparticles, predominately spherical in shape, have similar chemical structure, whatever the precursor employed. A higher crystallinity has been obtained for nanoparticles derived from iron chloride precursor, which present less agglomeration. The catalytic activity of as-prepared nanoparticles on the thermal decomposition of nitrocellulose (NC) was studied via differential scanning Calorimetry (DSC). Four isoconversional methods have been used to determine the kinetics triplets using the DSC data at different heating rates. It is revealed that the different nanocatalysts have a slight effect on the peak decomposition temperature of NC, whereas a notable decrease of the activation energy is obtained, especially for nanoparticles derived from iron chloride precursor. Finally, we can deduce that Fe2O3 prepared using iron chloride as a precursor may be safely used as an efficient catalyst for NC.