Liste des communications
Dephosphorization of Western Algerian Oolitic iron ore
A Combination of roasting and acid leaching processes was tested for the dephosphorisation of Gara Djebilet oolitic iron ore (Algerian Western Sahara) that contains a high phosphorus content of 0.91% which exceed-acceptable limits. A laboratory scale, this process involving a chemical attack after roasting of the raw sample of iron ore that mixed with alkaline additives (CaCl 2 or NaCl) followed by an acid leaching using nitric acid, perchloric acid, hydrochloric acid and sulfuric acid. 89% of phosphorus is removed by the addition of the salt (NaCl) then attacked by nitric acid. The laboratory tests carried out for a dephosphorisation show that the combination of roasting with alkaline additives, followed by an acid leaching makes it possible to obtain high quality iron concentrate. Despite the phosphorus content decreases from 0.91 to 0.1%. Voir les détails
Mots clés : Oolitic iron ore, acid leaching, dephosphorisation, alkaline additive.
Exploitation des sous-produits sidérurgiques du complexe Elhadjar -Annaba-.
Le présent travail de recherche se base sur l'exploitation du sous-produit sidérurgique (calamine) et sa transformation en produit utilisable dans le domaine des peintures anticorrosion. Ces oxydes de fer ont été examinés comme pigment et inhibiteur de corrosion dans deux types de peintures à concentrations différentes (1%, 3%, 7%, 15%) pour déterminer la meilleure formulation. Le meilleur temps de broyage de calamine est 2 minutes avec une distribution volumique D(0,9) des particules à une taille inférieure de 32 micromètre et une surface spécifique égale à 1.6 m2/g. L’analyse chimique montre une teneur en fer total moyenne de 72 % et des faibles teneurs en des oxydes de manganèse et de silice. L’analyse électrochimique a prouvé que les propriétés anticorrosives ou plutôt le rendement d’inhibition augmentent avec l’augmentation de concentration de la calamine dans les peintures testées (15% pour Glylac et 7% pour Glycar). Voir les détails
Mots clés : calamine, agent anticorrosif, analyse granulométrique, analyse électrochimique.
Acoustic emission source localization in plate-likestructure
This article proposes a geometric approach foracoustic emission source (AE) localization in plate-like structure.In order to determine the arrival time of the acoustic emissionwaves for each sensor with more precision, we have used twotechniques, the first one is based on thresholding and the secondis based on the continuous wavelet transform. Experimental testhave been carried out on steel plate shown that the continuouswavelet transform allows to be improve the accuracy of theacoustic emission source localization. Voir les détails
Mots clés : acoustic emission signal, acoustic emission source location, arrival time, threshold, continuous wavelet transform
ETUDE DE POLYMERE BIOSOURCE A BASSE DE POLY (ACIDE LACTIQUE) (PLA) PLASTIFIE AVEC DES PLASTIFIANTS VEGETAUX (ESTERS CITRIQUE)
Ces dernières années, le polyacide lactique (PLA) a attiré beaucoup d'attention comme un remplacement des plastiques issus du pétrole. Le PLA est fabriqué à partir de la fermentation du sucre ou de l'amidon. Il est de ressources renouvelables, biodégradables, alimentaires et non toxiques. Le PLA est utilisé dans les emballages alimentaires, la vaisselle jetable, mais aussi dans un certain nombre d'applications biomédicales, telles que les sutures, les stents et certains injecteurs de drogues [1,2]. Le polyacide lactique (PLA) est un polyester aliphatique présente une haute résistance, un haut module, cependant sa fragilité limite ses domaines d’application. Des efforts considérables ont été conduits pour modifier les propriétés de PLA [3,4]. L’objectif de ce travail est la plastification du PLA par l’utilisation des bio-plastifiants à base des esters citrique pour augmenter sa flexibilité. Lors de la préparation des différentes formulations nous utilisons le traitement thermique dans le plastographe Brabender. La plastification du PLA par Triéthyle citrique (TEC), Tributyle 2- acétyle citrique (TBAC), est réalisée par malaxage dans le plastographe Brabender à quatre compositions: 5, 10, 15, 20 et 30%. La spectroscopie infrarouge à transformée de Fourier (IRTF) indiquent qu'il y a des interactions moléculaires par liaison hydrogène intermoléculaire entre le PLA et les esters citriques (TEC et TBAC). Les résultats de diffraction des rayons X (DRX) confirment que le PLA n’avait pas de polymorphe de transition cristalline, les spectres UV-visible indiquent que les deux plastifiants (TEC et TBAC) n’ont pas d’effet sur la transparence et la coloration des films. Voir les détails
Mots clés : Polyacide lactique (PLA), Plastification, Triéthyle citrique (TEC), Tributyle 2- acétyle citrique (TBAC), biodégradable.
PLASTICIZING OF POLYLACTIC ACID (PLA) BIOPOLYMER WITH CITRATE ESTERS
Triethyl citrate (TEC) and acetyl tributyl citrate (ATBC) were used as plasticizer for Polylactic acid (PLA). The treated and plasticized PLA at various concentrations were analyzed by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), melt ?ow index (MFI) and thermogravimetric analysis (TGA). Differential scanning calorimetry was used to evaluate the crystallinity and thermal property of all the samples. It was found that the glass transition temperature (Tg) and the melting temperature (Tm) decreased as the amount of citrate esters increased. Additionally, the presence of TEC or ATBC tended to increase the crystallinity of PLA. This result was supported by x-ray diffraction. DMA of plasticized PLA indicates that a decrease in Tg is obtained with increasing plasticizer content, Plasticizing effect was also shown by decrease in the dynamic storage modulus and viscosity of plasticized mixtures compared to the treated PLA. The TGA results indicated that ATBC and TEC promoted a decrease in thermal stability of the PLA. Voir les détails
Mots clés : Polylactic acid (PLA), Plasticizer; Citrate esters; Crystallinity, Triethyl Citrate (TEC), Acetyl Tributyl Citrate (ATBC)
STUDY OF PLASTICIZED POLY (VINYL CHLORIDE) USING BIOBASED PLASTICIZERS MIXTURES
Poly (vinyl chloride) (PVC) is very present in daily living applications due to its diverse properties and low cost. Its properties depend on the amount of different kinds of additives such as plasticizers. The plasticizer is a very important additive of PVC; it can improve the flexibility of PVC without changing the chemical properties of the PVC. Phthalates are the most commonly used plasticizers in PVC with applications in food packaging, medical devices, children‘s toys, building materials, and other common products. Unfortunately, phthalates contaminate indoor environments, human food and are environmental contaminants. Several phthalates are suspected of having toxic effects.Biobased blends present potential use as nontoxic, sustainable plasticizers and as replacement of commonly used phthalate plasticizers. Epoxidised sunflower oil (ESO) and epoxidized sunflower oil methyl ester (ESOME) were prepared respectively by epoxidation and esterification reactions of sunflower oil (SO). Samples prepared by different combinations of ESO, ESOME, isosorbide (ISB) and acetyl tributyl citrate (ATBC) were blended with poly(vinyl chloride) (PVC) using two roll mills at 160°C. Discoloration sheets, mechanical properties, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to characterize the plasticized PVC.Discoloration change as well as thermal degradation decreases when increasing the amount of ESO or ESOME in plasticized systems. The effect of the four plasticizers systems on the glass transition temperature of PVC is similar; all samples exhibited both single Tg by DSC, which is in agreement with good miscibility of our formulations. Thus, combination of ESO, ESOME, ISB and ATBC performs a dual role in the stabilization and plasticization of PVC. Tensile strength at break of PVC formulations with different plasticizers mixtures reduces by decreasing the ESO or ESOME level, the elongation at break increases in the case of ISB with ESO or ESOME. The same with ATBC increases when rising ESO or ESOME.ATBC, ISB with 10 to 20 phr of ESO or ESOME are good candidates to substitute phthalates such as DEHP in flexible PVC formulations. Voir les détails
Mots clés : PVC, Epoxidation, Biobased Plasticizers, Environment.
Elaboration and characterization of electrodeposited cuprous oxide onto a sliver substrate
In this work, cuprous oxide thin films were prepared by using electrodeposition technique at different applied potentials from aqueous alkaline cupric sulfate solution with lactic acid at 70°C onto a sliver were investigated. The effects of deposition potential on the electrochemical, surface morphology, structural and, electrical properties of cuprous oxide thin films were investigated.The XRD measurements indicated that all the obtained films display a cuprous oxide cubic structure with a strong preferential orientation of the (111) direction.thin films, electrochemical, cuprous oxide, XRD Voir les détails
Mots clés : Thin films, electrochemical, cuprous oxide, XRD
Synthesis and characterization of Co doped ZnO prepare by dip-coating method
Abstract In this work, we studied deposited Cobalt- doped ZnO ( ZnO:Co ) thin films via dip-coating technique onto glass substrate, Zinc acetate dehydrate, cobalt acetate, 2- methoxyethanol and ethanolamine were used as starting materials. Then we have characterized them as X-ray diffraction , UV- visible, atomic force microscopy (AFM ). It is found that all the thin films have good crystallinity and a preferential orientation crystallites a long [002] of ZnO with wurtzite structure, and AFM have provided the information on morphology of this films where the size grain and average surface roughnes (Rms).thin films, ZnO, ( ZnO:Co ),dip-coating Voir les détails
Mots clés : Thin films, ZnO, ( ZnO:Co ), Dip-Coating
Electrochemical, Structural, and optical properties of Tin oxide thin films
ABSTRACT SnO2 thin films were electrodeposited on fluorine tin oxide substrate in nitric acid solution. The potential was swept from -0.4 to -1.6V with a rate of 50 mV/s. The films were found uniform, adherent to the substrate and amorphous. The XRD patterns reveal that after heat treatment at 500 °C for 1h, the films turn out to be crystalline in nature. Indeed, the film becomes composed of SnO2 nanocrystallite with a casseterite tetragonal structure. The nanocrystallite size is about 50 nm. The films thickness was found to be approximately 592nm and 563 nm for asdeposited and heat-treated SnO2 thin films, respectively. Some optical parameters of these films such as refractive index (n), extinction coefficient (k), absorption coefficient (α) and band gap were studied. Voir les détails
Mots clés : Thin films, SnO2, XRD
Complexity Reduction of UltrasoundSub-Ultra-Harmonic Modeling by an Input Modified Volterra Approach
Contrast of echographic images has been highly improved by the injection of microbubbles, due to their nonlinearbehavior. However, this contrast enhancement is limited by the nonlinear acoustic propagation in tissue. To overcome this drawback,sub and ultra-harmonic contrast imaging can be used, since only microbubbles can generate these components. Nonlinear modeling is aprimordial step in the analysis of microbubble signals for sub and ultra-harmonic imaging. Nonlinear models like Volterra model hasbeen applied in harmonic imaging to model harmonics optimally. However, it can model harmonics only. For sub and ultra-harmonicmodeling, a multiple input single output (MISO) Volterra has been proposed. The aim of this study is to propose a simpler alternativefor the modeling of sub and ultra-harmonics. We propose a modified single input single output (SMISO) Volterra model based on inputdemodulation. The model is tested using simulated and experimental signals. Results showed that sub and ultra-harmonics aremodeled. The number of kernels is reduced to its half using SMISO model compared to MISO model. The relative mean square errorbetween the simulated signal and the modeled signal with SMISO Volterra model is −15.8 dB and it is −60.7 dB for experimentalsignals. The computational time is reduced by a factor of 4 and 5 in simulated and experimental cases respectively. SMISO model canmake easier the sub and ultra-harmonics modeling. Voir les détails
Mots clés : modeling, sub-ultra-harmonics, SMISO Volterra, demodulation, microbubble.