Conception de nouveaux composites élastomères utilisés en ingénierie de fabrication : effet des conditions de traitement de vulcanisation, les propriétés physiques, chimiques, mécaniques et viscoélastiques

Cette thèse a plusieurs objectifs différents. La première est de concevoir de nouveaux composites élastomères charge renforcée sur la base de mélange de deux types d'élastomères différents vulcanisés dans des conditions différentes (température de vulcanisation, système de vulcanisation etc.) afin d'obtenir de meilleures performances de traitement et de propriétés. La deuxième est de caractériser les mélanges nouvellement créées en utilisant différentes méthodes et différentes conditions de fonctionnement. Le troisième est d'étudier la possibilité de remplacer une partie de la charge conventionnelle (noir de carbone) avec de la résine époxy ou l'utilisation de particules fines comme le SiC et Al2O3. Au stade final de la thèse, nous avons proposé des conditions de travail optimales et les applications industrielles. Une proposition très pratique a été donnée pour l'optimisation de la composition pour différentes applications industrielles. À la suite de la recherche à l’échelle industrielle qui est l'objet de cette thèse, nous avons proposé des compositions originales de haute qualité adaptés pour différentes applications.This thesis has several different aims. First one is to design new filler-reinforced elastomeric composites based on mixing together of two different types of elastomers vulcanized under different conditions (vulcanization temperature, vulcanization system, etc.) in order to obtain better processing and performance properties. Second one is to characterize the newly created mixtures by using variety of methods and different operating conditions. The third one is to investigate the possibility to replace part of the conventional filler (carbon black) with epoxy resin or the use of fine particles as SiC and Al2O3. At the final stage of the thesis, we have suggested the optimal working conditions and industrial applications. A very practical proposal was given for the optimization of the composition for different industrial applications. As a result of the full scale investigation which is the object of this thesis, we have proposed original high quality compositions suitable for different engineering applications

Carbonate apatite formation on novel multiphase CaO-SiO2-P2O5-MgO glass-ceramics in TRIS-HCl buffer

The main purpose of the presented article is the preparation of novel glass-ceramics in CaO-SiO2-P2O5-MgO system and evaluation of carbonate apatite formation after soaking in TRIS-HCl buffer solution for 14 days. The investigated samples were prepared via sol-gel method and structure of the obtained samples was studied using XRD, FTIR, SEM, XPS and ICP-AES. XRD of the thermally treated samples showed that the presence of some crystalline phases is depended on the gel composition. FTIR revealed the existence of all characteristic bands for the observed crystalline phases. SEM monitored the presence of particles with different morphology. After soaking in TRIS-HCl solution, FTIR confirmed that carbonate apatite was formed on the soaked surface. The obtained data are in a good agreement with XPS analysis. The change of ions concentrations in TRIS-HCl buffer solution after immersion of the prepared glass-ceramics was recorded by ICP-AES measurements

In Vitro Bioactivity of Silver-Containing Sol-Gel Glasses: FTIR Analysis

Introduction: The sol-gel glasses (BG) have been used for various biomedical applications, such as orthopedic, dental grafting and tissue engineering. The main purpose of the presented article is the preparation and evaluation of carbonate apatite formation on the BG in SiO2-CaO-P2O5-xAg2O system, where x=0,1,2 and 4wt.% Ag2O (BG/Ag), after soaking in a simulated body fluid (1.5 SBF) for 12 days in static conditions.Materials and Methods: BG/Ag were synthesized from tetraethyl orthosilicate (TEOS), calcium oxide (CaO), phosphoric acid (H3PO4) and silver nitrate (AgNO3) as sources. TEOS was stirred into the mixed solvent of C2H5OH and H2O with a very small amount of HCl in the volume ratio TEOS:C2H5OH:H2O:HCl=1:1:1:0.01. The mixture of calcium phosphate (CP) and appropriate amount of AgNO3 was added to SiO2 sol under stirring for 20h. The mixed sol obtained was gelated at 120oC for 12h and 600oC for 6h.Results: X-ray powder diffraction (XRD) of the synthesized samples showed that the presence of some crystalline phases is dependent on the gel composition. XRD proved the presence of CaCO3, wollastonite, HA and metallic Ag in accordance with gel compositions. Fourier transform infrared spectroscopy (FTIR) of the prepared BG showed the presence of basic absorption bands, corresponding to the different chemical bands and crystalline phases, in agreement with XRD results. FTIR of the examined samples, after soaking in 1.5 SBF solution for 12 days, confirmed that B-type carbonate apatite was formed preferentially on the soaked surface.Conclusions: BG in SiO2-CaO-P2O5-xAg2O system (x=0,1,2 and 4wt.% Ag2O) were synthesized via a polystep sol-gel method. After immersion of the studied BG in 1.5 SBF solutions for 12 days in static conditions, FTIR revealed the presence of some CO32- bands, i.e. after soaking carbonate apatite (CO3HA) may be formed on the surface of the prepared sol-gel glasses. On the basis of FTIR results, we can assume that B-type CO3HA preferentially formed on the soaked samples

Wear resistance of elastomeric based composites by continuous multi-cycle indentation used in manufacturing engineering

Wear resistance is an important rubber compound property related to useful product life. The rubber compound properties that affect wear behavior are very complicated. Wear is related to a rubber compound\u27s cut resistance, tear resistance, fatigue resistance hardness, etc. The most commonly used test method to determine the wear resistance of rubber materials is abrasion test. Tested compounds are usually compared on a volume loss basis which is calculated from the weight loss and density of the compound. This method is known to be variable and doesn\u27t give additional information for the wear behavior. For this reason we propose alternative approaches for examination of the wear behavior of rubber composites, giving information not only for the wear resistance but also for elastic the modulus, stiffness of the material, damage mechanism, etc. Continuous multi-cycle indentation is used to determine the indentation hardness, elastic modulus and the stiffness with two indenter types -Vickers and sphero-conical. Comparison of both results is made in order to investigate the effect of the indenter type. © (2014) Trans Tech Publications, Switzerland

Design of multifunctional energetic structural composites: A preliminary study on an epoxy-rubber matrix with exothermic mixture reinforcements

A new multifunctional energetic structural composite was designed in the frame of a common research project for potential applications as structural energetic materials in aeronautical engineering. A mixture of structural and energetic functions can be achieved using different reinforcements in rubber-epoxy composites and this type of design give an exigent task. The mechanical and physical properties of the various composite systems containing Nickel and extremely fin aluminium and powders in a epoxy-rubber matrix were studied to investigate their mechanical physical properties. Dynamic (impact choc) tests and static compression tests have been carried out to understand failure response of these composites. Microstructural characterization can reveal that micro-sized Ni and Al stayed on homogeneously and intimately mixed within the epoxy matrix. Dielectric properties and dielectric loss angle tangent (tan delta) were investigated using a Dielectric Thermal Analyzer (DETA). Viscoelastic properties have been evaluated by microindentation tester and also surface wear resistance were measured by scratch test device

Manufacturing and damage analysis of filler reinforced epoxy-based composites

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New design of aluminium based composites through combined method of powder metallurgy and thixoforming

The present study deals with a new design of aluminium alloy based composites reinforced with SiC particles and Si/Al2O3 powders through combined methods of powder metallurgy and thixoforming. Moreover, recycled machining chips are used as raw material, specifically AA7075 chips generated in the aeronautical industry. The proposed method is based on forming at high temperatures a compacted mixture of metal chips and reinforcing particles, with the metal in thixotropic semi-solid condition. Composites containing different SiC weight fractions (10, 20 and 30%) were produced and had their microstructure analyzed. Mechanical properties were evaluated by means of micro-indentation tests. General results show the feasibility of producing composites by the proposed route. Products with good mechanical properties could be obtained. The process, even still not completely optimized as some improvement still must be achieved, can bring a new possibility for the production of a noble material from recycled wastes, particularly important in the high energy spending Al industries939687

In vitro bioactivity of glass-ceramic/fibroin composites

Bioactive composite materials were prepared by mixing 20 wt.% of silk fibroin (SF) and 80 wt.% of glassceramics from CaO-SiO2-P2O5-MgO system. In vitro bioactivity of the prepared composites was evaluated in 1.5 simulated body fluid (1.5 SBF) in static conditions. The obtained samples before and after in vitro tests were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The changes in 1.5 SBF solutions after soaking the samples were evaluated by inductively coupled plasma atomic emission spectroscopy (ICP-AES). MG63 osteosarcoma cells were used for the biological experiments. The obtained experimental data proved that the synthesized composites exhibit excellent in vitro bioactivity