Browsing by Author "Ouslimani, Nassira"

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    Absorption performances of PLA-Montmorillonite nanocomposites thin films in salisbury and rozanov configurations : influence of aging and mechanical recycling
    (MDPI, 2023) Sidi Salah, Lakhdar; Ouslimani, Nassira; Danlée, Yann; Huynen, Isabelle
    The present paper aims to address the crucial concern of pollution induced by growing plastic waste and electromagnetic interference (EMI). Nanocomposites combining poly(lactic acid) (PLA) and organo-modified montmorillonite (OMMT) are synthesized and compression molded into thin films. A first set of samples, referred as virgin, was kept as is, while a second set of samples were photochemically, thermally and hydrolytically aged before mechanical recycling via extruding and second compression molding, resulting in the so-called recycled composite. The electromagnetic (EM) properties with a focus on microwave absorption performances of virgin and recycled samples are compared for various thicknesses and weight concentrations of OMMT in PLA matrix. The EM performances are gauges by Rozanov and Salisbury structures that consist in one- and two-layer stacks of composite films back-coated by a metal foil. Characterization in Rozanov configuration shows an average absorption index over the Ka band of 29.3% and 21.1% for, respectively, virgin and recycled PLA reinforced with 4 wt.% OMMT. An optimization of the film thickness is proposed; up to 61.85% and 80% of absorption with a thickness of 1.4 mm and 3.75 mm, respectively, is reached with a metal back-coated rPLA-4%OMMT film. Characterization in Salisbury configuration gives advantage to the recycled structure with an average absorption of 49.6% for a total thickness of 1.4 mm. The requirements of EMI shielding are met by PLA-OMMT composites with a certain benefit of recycling process on EM performance
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    Adsorption des colorants acides des effluents manufacturiers par des montmorillonites
    (2012) Ouslimani, Nassira
    Des colorants textiles Industriels sont présents dans les eaux usées à des concentrations différentes. Ils représentent la principale source de la contamination environnementale dans les eaux usées. Ils doivent être retirés des eaux usées par différentes méthodes. Une des méthodes les mieux connues est l'adsorption des colorants sur des solides à grande surface spécifique tels que des argiles comme la bentonite. L'étude de ces matériaux a été réalisée en utilisant la diffraction DRX, l'analyse thermique, (DTA et TG, la spectroscopie infrarouge (IR) et l'analyse chimique. Il a été constaté que le matériau utilisé est composé principalement de montmorillonite. Cette argile a été ensuite purifiée et transformée en argile homoionic saturée en ions sodium. Ces bentonites (brute et sodique) ont été utilisées pour l'adsorption des colorants acides rouge et jaune. Différents paramètres ont été testés tels que; le temps, le pH, la température et la concentration des colorants. Il a été constaté que les données optimum sont atteints à 240 mn, pH 2 et 19 ° C.Les Isothermes d'adsorption montrent que les meilleurs résultats sont obtenus en utilisant la bentonite purifiée et transformée en forme sodique. La capacité ultime de l'adsorption est égale à 12,19 mg / g et 1,075mg / g respectivement pour le colorant jaune et le colorant rouge
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    Adsorption of yellow bemacid CM-3R dye from aqueous solutions onto raw and sodium bentonite
    (2012) Ouslimani, Nassira; Zibouche, Fatima; Iratni, A.; Abadlia, Mohamed Tahar
    Discharges from the textile industries are heavily loaded with various dyes which requires their treatment. The most common method is to adsorb on solids high surface area, for example, clay material highly available and whose leaves are good natural adsorbents. In present study we used a local bentonite available in its natural form and sodium form for the adsorption of a dye CM-3R yellow bemacid provided by BEZEMA. The evaluation of the effect of various variables is driven by a series of experiments as the contact time, initial concentration of the dye, the initial pH. The different parameters show that the adsorption of the dye is favoured to 240 min, pH 2 and a temperature of 19 ºC. The sodium bentonite yielded good performance results due to the improvement of its adsorption properties. The best correlation of experimental results are obtained with the Langmuir model for sodium bentonite (R % = 0.998) and Freundlich for the raw bentonite (0997)
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    Carbon nanotubes (CNTs) from synthesis to functionalized (CNTs) using conventional and new chemical approaches
    (2021) Lakhdar, Sidi Salah; Ouslimani, Nassira; Bousba, Dalila; Huynen, Isabelle; Danlée, Yann; Aksas, Hammouche
    Carbon nanotubes (CNTs) have emerged worldwide because of their remarkable properties enlarging their field of applications. Functionalization of CNTs is a convenient strategy to tackle low dispersion and solubilization of CNTs in many solvents or polymers. It can be done by covalent or noncovalent surface functionalization that is briefly discussed regarding the current literature. Endohedral and exohedral are conventional methods based on covalent and van der Waals bonding forces that are created through CNT functionalization by various materials. In this paper, a review of new approaches and mechanisms of functionalization of CNTs is proposed, including amidation, fluorination, bromination, chlorination, hydrogenation, and electrophilic addition. Our analysis is supported by several characterization methods highlighting recent improvements hence extending the range of applicability of CNTs.
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    Effect of Modified Nanoclays on the Mechanical Properties of Thermoplastics Polymer Nanocomoposites
    (Université M'hamed Bougara de Boumerdès, 2020) Ouslimani, Nassira; Kouini, Benalia; Boumerdassi, K.
    Nanocomposites based on polypropylene/polyamide66 (PP/PA66) nanoblends containing organophilicmontmorillonite(OMMT) and maleic anhydride grafted polypropylene (PP-g-MAH) were prepared by melt compounding method followed by injection molding. Two different types of nanoclayswere used in this work, i.e. DELLITE LVF (untreated): is a nano-clay deriving from a naturally occurring especially purified montmorillonite and DELLITE 67G (treated with a high content of quaternary ammonium salt (dimethyl dehydrogenated tallow ammonium). The rheological results revealed a drastic reduction in MFI with a levelling off at 5 wt.% for the nanoblends containing treated clay. The impact properties of PP/PA66 modified nanoblendswere improved significantly in the presence of treated nanoclay. The morphology of the nanocompositeswas studied using the XR diffraction (XRD). XRD results revealed the formation of nanoblends as the nanoclaywas intercalated and exfoliated.
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    Influence of various parameters on the stability of a paste foamed
    (2013) Ouslimani, Nassira; Mazouz, A.; Mazouz, A.; Benferrah, N.
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    Investigation of mechanical recycling effect on electromagnetic properties of polylactic acid (PLA) – nanoclay nanocomposites : towards a valorization of recycled PLA nanocomposites
    (Elsevier, 2023) Sidi Salah, Lakhdar; Ouslimani, Nassira; Danlée, Yann; Beltrán, Freddys R.; Huynen, Isabelle; Ulagares de la Orden, María
    Virgin and recycled poly(lactic acid) (PLA) based nanocomposite materials were obtained and subjected to microstructural, thermal and mechanical analysis in view of fabricating efficient microwave absorbers. PLA was first exposed to artificial accelerated aging, next was mechanically recycled through grinding followed by reprocessing using melt extrusion and compression molding, resulting in recycled PLA samples (rPLA). Addition of organically modified montmorillonite (OMMT) as nanoclay was performed in a second melt extrusion process in order to obtain virgin and recycled PLA-OMMT nanocomposites. The impact of recycling process and presence of OMMT nanoclay in the host PLA matrix has been studied by FTIR, TGA and DSC, while the mechanical performance has been investigated by micro-hardness test. The dielectric properties were measured in the 26–40 GHz frequency range using a Vector Network Analyzer to assess the performance of virgin and recycled PLA and OMMT-PLA material as microwave absorbers. The FTIR results show that the recycling process generated more C = O groups in the polymer. These polar groups tend to orient themselves in the direction of the applied field and increase the dielectric constant (ε'). Measured electromagnetic absorption index revealed that rPLA-4OMMT with a thickness of 400 µm is able to absorb 20.3% on average of the spectrum with a peak of 36%, while 200 µm-thick films of rPLA-4 wt.% OMMT has a mean absorption index of 14.5%. The overall results show that mechanically recycled polymer can replace virgin polymer in this kind of applications
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    Predictive optimization of electrical conductivity of polycarbonate composites at different concentrations of carbon nanotubes: A valorization of conductive nanocomposite theoretical models
    (MDPI, 2021) Sidi Salah, Lakhdar; Ouslimani, Nassira; Chouai, Mohamed; Danlée, Yann; Huynen, Isabelle; Aksas, Hammouche
    Polycarbonate—carbon nanotube (PC-CNT) conductive composites containing CNT concentration covering 0.25–4.5 wt.% were prepared by melt blending extrusion. The alternating current (AC) conductivity of the composites has been investigated. The percolation threshold of the PC-CNT composites was theoretically determined using the classical theory of percolation followed by numerical analysis, quantifying the conductivity of PC-CNT at the critical volume CNT concentration. Different theoretical models like Bueche, McCullough and Mamunya have been applied to predict the AC conductivity of the composites using a hyperparameter optimization method. Through multiple series of the hyperparameter optimization process, it was found that McCullough and Mamunya theoretical models for electrical conductivity fit remarkably with our experimental results; the degree of chain branching and the aspect ratio are estimated to be 0.91 and 167 according to these models. The development of a new model based on a modified Sohi model is in good agreement with our data, with a coefficient of determination R2 = 0.922 for an optimized design model. The conductivity is correlated to the electromagnetic absorption (EM) index showing a fine fit with Steffen–Boltzmann (SB) model, indicating the ultimate CNTs volume concentration for microwave absorption at the studied frequency range. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
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    Valorization of fibrous waste for the wastewater discoloration
    (2013) Ouslimani, Nassira; Zrari, F.; Abadlia, Mohamed Tahar; Benabed, H.