Publications Scientifiques

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    Viscosity-boosting effects of polymer additives in automotive lubricants
    (Springer Nature, 2024) Boussaid, Mohamed; Haddadine, Nabila; Benmounah, Abdelbaki; Dahal, Jiba; Bouslah, Naima; Benaboura, Ahmed; El-Shall, Samy
    This study investigated polyethylene glycol (PEG), as a polymer improver of the paraffinic oil viscosity index (VI). The characterization of PEG/paraffinic oil blends at different concentrations (0%, 1%, 2%, 3%, 5%, and 10%), was performed using Raman spectroscopy and optical microscopy. The rheological parameters as the viscosity index and activation energy were determined using the kinematic viscosity measurements. Results showed that the VI improvement reached an optimal value for the blend containing 3% PEG, with greater value for blends containing 2% PEG than 5 and 10% PEG. The presence of polymer particles was observed by optical microscopy, which confirmed the lack of PEG distribution in the blend containing 5%, and more, whereas mixtures with 3 and 2% PEG exhibited good particle distribution, evidenced by smaller polymer particle sizes. This finding was corroborated by Raman spectroscopy, which revealed the absence of polymer–oil intermolecular interactions in the PEG/paraffinic oil blends. The rheological tests showed that increasing the blend temperature from 40 to 80 ℃, improved the PEG chains dispersion in the paraffin oil, for the blends containing up to 3% PEG. The difference of the activation energy of the pure paraffinic oil and the PEG/paraffinic oil blends, (ΔEa) was calculated, and the correlation between the ΔEa and the viscosity index values was established. Therefore, adding PEG to paraffinic oil appeared to be promising for the viscosity index improvement and promote industrial applications of paraffinic oil.
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    Excitation and spectral dependence of the rise and decay time responses of Eu2+- and Dy3+-doped strontium aluminates
    (Springer, 2022) Fouzar, Samia; Kostova, Irena; Eftimov, Tinko; Benmounah, Abdelbaki; Ouchabane, Mohammed; Lakhssassi, Ahmed
    In this paper, we study the phosphorescence rise and decay time responses of Eu2+- and Dy3+-doped strontium aluminates prepared by different methods after scanning them with a narrow spectral width (15 nm FWHM) light from a monochromator. The experiments performed show that the time responses essentially depend on the excitation duration as well as on the excitation and the emission wavelengths. It has been found that at the excitation wavelength of maximum efficiency λ′max, a ‘fast track’ rise and decay of the phosphorescence exists. We suggest that by studying the normalized switch on and switch off time responses, we can determine the relative share of slow phosphorescence afterglow with respect to fast and slow phosphorescence decay as well as the rate of luminescence rise and decay processes. The relation to the synthesis technology and to the contents of the samples is discussed
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    Rheological study of sodium carboxymethylcellulose: Effect of concentration and molecular weight
    (Elsevier, 2022) Chalah, Kaci; Benmounah, Abdelbaki; Mahdad, M'hamed; Kheribet, Rabia
    This study deals with the rheological behavior of sodium carboxymethylcellulose (Na-CMC) using a rheological analysis. The rheological properties of Na-CMC in aqueous solution, at different mass concentrations (0.7, 0.9, 1.1, 1.3 and 1.5 wt%) and types including carboxymethylcellulose high viscosity (CMC HV), medium viscosity (CMC MV) and low viscosity (CMC LV), were investigated using a large deformation rheological measurements (0–700 s−1). The rheological behavior of CMC HV and CMC MV solutions was shear-thinning without yield stress. The flow curves were modeled by Ostwald de Waele and Cross laws (R2 > 0.99). The same models were used for fitting flow curves of various samples of CMC LV suspension but we noticed shear thickening behavior. On the contrary of the CMC HV and CMC MV, and according to the power law model, the flow index of CMC LV was increased with raising in concentration. The consistency of Na-CMC solution at 0.7w.% were 0.5 × 10−3, 0.039 and 0.252 Pa·s, and at 1.5%-CMC were 0.5 × 10−3, 0.065 and 3.162 Pa·s, for respectively CMC LV, CMC MV and CMC HV
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    Effects of temperature on the time responses of strontium aluminates
    (Elsevier, 2021) Fouzar, Samia; Eftimov, Tinko; Kostova, Irena; Benmounah, Abdelbaki; Lakhssassi, Ahmed
    In this paper we study the effect of temperature on the rise and decay time responses of Eu and Eu, Dy doped strontium aluminates. Normalized switch on and switch off time responses are used to estimate the share of phosphorescence in the observed luminescence. The parameters of the power law time responses related to the relative share of phosphorescence in luminescence and to the rise/decay rates are found to be strongly temperature dependent. The results show that unlike luminescence intensity, the overall efficiency of phosphorescence increases strongly with temperature and reaches a maximum around 65 °C. Thе maximum correlates with the activation energy of the samples and depends on their doping and fabrication technology
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    Comparative studies of the rheological behavior and microstructural properties of emulsions (oil/distilled water phase) and (oil/Lias water phase)
    (Taylor and Francis, 2018) Djemiat, Djamal Eddine; Safri, Abdelhamid; Benmounah, Abdelbaki
    The rheological behavior of crude oil and their emulsions were investigated as a function of two water types (distilled water and the LIAS water). The focus of this work is to obtain more knowledge about the effect of LIAS water concentration, which used to maintain pressure and produced from production of crude oil in the oil fields Tin Fouye Tabankort-south Algeria, on the rheological properties of crude oil. The rheological parameters were measured by using AR-2000 rheometer at 15 °C under dynamic and shear testing conditions. The measured data were first classified into two groups for Newtonian and non-Newtonian fluids. Depends on the type and concentration of water, the non-Newtonian behavior was described in better way by the Casson, Power law and the Herschel–Bulkley models. The results indicated that the viscosity, the yield stress, the elastic modulus, (G′), the loss modulus, (G″), and the microstructure of the prepared emulsions not only varied with water concentration but also by water types.
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    Improvement of rheological properties of Algeria crude oil by addition of extra-light crude oil and a surfactant agent
    (Taylor and Francis Online, 2018) Djemiat, Djamal Eddine; Safri, Abdelhamid; Benmounah, Abdelbaki
    Effect of surfactant and extra-light crude oil addition on the rheologicalbehaviors of an Algeria crude oil in order to improving its flowability werestudied at low temperature. These rheological properties include steadyflow behavior, yield stress and viscoelastic behavior. An AR-2000 rheometerwas employed in all of the rheological examination tests. Results showthat Toluene and extra-light crude oil addition causes a strong reductionin viscosity, the yield stress and can effectively increase of crude oil trans-port capacity. The toluene addition gets its best flow capacity and lowestviscosity at 6%. The extra-light crude oil addition obtains its best flow cap-acity and lowest viscosity at 50%. The viscoelasticity character of the crudeoil has indicate a significantly influence by the addition of Toluene andextra-light crude oil.
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