Materials and processes used for medical applications should have specific attributes. For bone repair and reconstruction, controlled open porosity and osteoconductivity are essential apart from mechanical strength and biocompatibility. Several forms of calcium phosphates are often used for these applications, considering properties similar to bone minerals, but often in combinations with other biopolymers. Polymethyl methacrylate (PMMA) and β-tricalcium phosphate (β-TCP) are identified as a suitable combination for the current research, considering specific properties both individually and in combinations, when processed by different means for specific medical applications. Specific responses of the biocomposite material formed by mechanically mixing the two materials in the powder form to selective laser sintering (SLS) under varying conditions are investigated. The results indicate the suitability of the material system for SLS, while controlled porosity and mechanical property combinations are possible by optimizing material composition and process parameters.

Dans les matériaux fragiles, la mécanique linéaire élastique de la rupture (MLER) préditune énergie de fracture constante et une vitesse de fissuration limitée par la vitesse deRayleigh (CR). Or un grand nombre d’expériences contredisentces prédictions. Pour comprendre ce désaccord, nous avons développé un dispositif derupture dynamique dans un matériau fragile modèle – le PMMA. Nous montrons l’existenced’une divergence de l’énergie de fracture à 0,2 CR due à unetransition fragile/quasi-fragile. Nous suggérons qu’un modèle géométrique pourra aider àmieux comprendre la dynamique de propagation et d’endommagement.

This work is about the production of hybrid coatings of the system SiO2-PMMA (PMMA, polymethylmethacrylate). These materials have interesting mechanical and chemical properties useful for anticorrosive and wear resistance applications. SiO2-PMMA hybrids were obtained by the sol-gel traditional process, using tetraethylorthosilicate (TEOS) and methylmethacrylate (MMA) by Aldrich Co, as starting reagents. The SiO2:PMMA ratio was varied from 0:1 to about 1:1 at air atmosphere deposition. The coatings were obtained on acrylic sheets and silicon wafers. A diversity of coatings with chemical composition ranging from SiO2 and PMMA to obtain the SiO2-PMMA hybrids were obtained. Infrared (IR) and atomic force microscopy (AFM), were performed to determinate structural and morphological behavior.

On étudie un lot de plaquettes de PMMA avec branchements, obtenues sous compression uniaxiale pour un défaut oblique fermé par différents matériaux (Téflon, acier dur, bronze, laiton, acier doux, plomb, aluminium et cuivre) et faisant un angle d'inclinaison β variable de 15 à 75° par rapport à la direction de la charge imposée, en déterminant d'une part la distance δ entre le front de l'entaille et la racine du branchement mesurée parallèlement à l'axe de l'entaille, et d'autre part l'angle de branchement θ entre la direction de l'entaille et la tangente à la racine de la fissure branchée.