Ti-Mo alloys employed as biomaterials: Effects of composition and aging heat treatment on microstructure and mechanical behavior

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Vegetable Oil Derived Solvent, and Catalyst Free Click Chemistry'' Thermoplastic Polytriazoles

Azide-alkyne Huisgen click chemistry provides new synthetic routes for making thermoplastic polytriazole polymers-without solvent or catalyst. This method was used to polymerize three diester dialkyne monomers with a lipid derived 18 carbon diazide to produce a series of polymers (labelled C18C18, C18C9, and C18C4 based on monomer chain lengths) free of residual solvent and catalyst. Three diester dialkyne monomers were synthesized with ester chain lengths of 4, 9, and 18 carbons from renewable sources. Significant differences in thermal and mechanical properties were observed between C18C9 and the two other polymers. C18C9 presented a lower melting temperature, higher elongation at break, and reduced Young's modulus compared to C18C4 and C18C18. This was due to the odd-even effect induced by the number of carbon atoms in the monomers which resulted in orientation of the ester linkages of C18C9 in the same direction, thereby reducing hydrogen bonding. The thermoplastic polytriazoles presented are novel polymers derived from vegetable oil with favourable mechanical and thermal properties suitable for a large range of applications where no residual solvent or catalyst can be tolerated. Their added potential biocompatibility and biodegradability make them ideal for applications in the medical and pharmaceutical industries.

Mechanical and Thermal Properties of Thermoplastic Random Copolyesters Made from Lipid- Derived Medium and Long Chain Poly (x-hydroxyfatty acid) s

The physical properties of novel thermoplastic random copolyesters [-(CH2)(n)-COO-/-(CH2)(n)-COO-](x) made of long (n=12) and medium (n=8) chain length -hydroxyfatty esters [HO-(CH2)(n)-COOCH3] derived from bio-based vegetable oil feedstock are described. Poly(-hydroxy tridecanoate/-hydroxy nonanoate) P(-Me13-/-Me9-) random copolyesters (M-n=11,000-18,500 g/mol) with varying molar ratios were examined by TGA, DSC, DMA and tensile analysis, and WAXD. For the whole range of P(-Me13-/-Me9-) compositions, the WAXD data indicated an orthorhombic polyethylene-like crystal packing. Their melting characteristics, determined by DSC, varied with composition suggesting an isomorphic cocrystallization behavior. TGA of the P(-Me13-/-Me9-)s indicated improved thermal stability determined by their molar compositions. The glass transition temperature, investigated by DMA, was also found to vary with composition. The crystallinities of P(-Me13-/-Me9-)s however, were unaffected by the composition. The stiffness (Young's modulus) of these materials was found to be related to their degrees of crystallinity. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40492.

Characterization of a polymer-infiltrated ceramic-network material

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Nanocomposites of natural rubber and polyaniline-modified cellulose nanofibrils

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito de tratamentos térmicos nas propriedades mecânicas, eletroquímicas e citotoxidade de ligas do sistema Ti-15Mo-XNb

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of monomeric and polymeric structure on the physical properties of thermoplastic polyesters derived from hydroxy fatty acids

The physical properties of three vegetable oil derived medium and long chain poly(-hydroxy fatty ester)s (P(Me--OHFA)s), namely poly(-hydroxynonanoate) [P(Me--OHC9)], poly(-hydroxytridecanoate) [P(Me--OHC13)] and poly(-hydroxyoctadecanoate) [P(Me--OHC18)] (n = 8, 12 and 17, respectively), of the [-(CH2)(n)-COO-](x) polyester homologous series are presented. The effect of M-n (M-n 10-40 kg mol(-1)) and n on the crystal structure and thermal and mechanical properties of the P(Me--OHFA)s were investigated by wide-angle X-ray diffraction (WAXD), TGA, DSC, dynamic mechanical analysis (DMA) and tensile analysis and are discussed in the context of the [-(CH2)(n)-COO-](x) polyester homologous series, contrasted with linear polyethylene (PE). For all P(Me--OHFA)s the WAXD data indicated an orthorhombic crystal phase reminiscent of linear PE with crystallinity (X-c = 50%-80%) depending strongly on M-n. The glass transition temperature and Young's modulus for P(Me--OHFA)s increased with X-c. The DSC, DMA and TGA studies for P(Me--OHFA)s (n = 8, 12 and 17) indicated strong correlations between the melting, glass transition and thermal degradation behavior and n. The established predictive structure relationships can be used for the custom engineering of polyester materials suitable for specialty and commodity applications. (c) 2014 Society of Chemical Industry

One-dimensional silicon and germanium nanostructures with no carbon analogues

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of Ceramic Thickness and Shade on Mechanical Properties of a Resin Luting Agent

Purpose: This study aimed to investigate the influence of ceramic thickness and shade on the Knoop hardness and dynamic elastic modulus of a dual-cured resin cement.Materials and Methods: Six ceramic shades (Bleaching, A1, A2, A3, A3.5, B3) and two ceramic thicknesses (1 mm, 3 mm) were evaluated. Disk specimens (diameter: 7 mm; thickness: 2 mm) of the resin cement were light cured under a ceramic block. Light-cured specimens without the ceramic block at distances of 1 and 3mm were also produced. The Knoop hardness number (KHN), density, and dynamic Young's moduli were determined. Statistical analysis was conducted using ANOVA and a Tukey B rank order test (p = 0.05).Results: The bleaching 1-mm-thick group exhibited significantly higher dynamic Young's modulus. Lower dynamic Young's moduli were observed for the 3-mm-thick ceramic groups compared to bleaching 3-mm-thick group, and no difference was found among the other 3-mm groups. For the KHN, when A3.5 3-mm-thick was used, the KHN was significantly lower than bleaching and A1 1-mm-thick ceramic; however, no difference was exhibited between the thicknesses of the same shade.Conclusions: The dual-cured resin cement studied irradiated through the 1-mm-thick ceramic with the lightest shade (bleaching ceramic) exhibited a better elastic modulus, and there was no effect in KHN of the resin cement when light cured under different ceramic shades and thicknesses (1 and 3 mm), except when the A3.5 3-mm-thick ceramic was used.Clinical Significance: Variolink II irradiated through ceramic with the lowest chroma exhibited the highest elastic modulus; therefore, the light activation method might not be the same for all clinical situations.

Desenvolvimento de um novo sistema dinâmico para avaliação da liberação de fármacos

Pós-graduação em Biociências - FCLAS

Desenvolvimento de uma nova liga quaternária Ti25Ta25Nb3Sn para aplicações odontológicas

Pós-graduação em Engenharia Mecânica - FEG

Desenvolvimento e avaliação de um sistema de liberação sustentada de gentamicina em biomembranas de látex natural

Pós-graduação em Biociências - FCLAS

Membranas de biocelulose como substrato para o crescimento de nanofios de ZnO: síntese e aplicação

Pós-graduação em Química - IQ

Production of a low young modulus titanium alloy by powder metallurgy

Titanium alloys have several advantages over ferrous and non-ferrous metallic materials, such as high strengthto-weight ratio and excellent corrosion resistance. A blended elemental titanium powder metallurgy process has been developed to offer low cost commercial products. The process employs hydride-dehydride (HDH) powders as raw material. In this work, results of the Ti-35Nb alloy sintering are presented. This alloy due to its lower modulus of elasticity and high biocompatibility is a promising candidate for aerospace and medical use. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by isochronal sintering between 900 up to 1600 °C, in vacuum. Sintering behavior was studied by means of microscopy and density. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. Samples sintered at high temperatures display a fine plate-like alpha structure and intergranular beta. A few remaining pores are still found and density above 90% for specimens sintered in temperatures over 1500 °C is reached.