Materials Science Forum Vol. 805

Abstract: This work aim to functionalize the ZnAl_1.9Eu_0.1O₄ spinel with ethylenediamine and methylmethacrylate monomer mixtures. ZnAl_1.9Eu_0.1O₄ nanoparticles were obtained according to the theory of propellants and explosives by combustion reaction. The samples were added to the silane agent 3-aminopropyltriethoxysilane. After silanized were functionalized with a monomers mixture. By X-ray diffractogram, it was observed the formation of a major phase of ZnAl₂O₄ cubic normal spinel and the secondary phase EuAlO₃. The FTIR spectra for ZnAl_1.9Eu_0.1O₄ exhibit absorption bands below 1000 cm ^-1, and after the functionalization showed two conjugate bands that were attributed to the presence of free NH₂ groups and the binding of oxygen to the group NH₂, and strips Si-O, originating from the silane agent. The emission spectra for samples before and after functionalization showed spectral lines ⁵D₀ → ⁷F₀, ⁷F₁ → ⁵D₀, ⁵D₀ → ⁷F₂, ⁷F₃ → ⁵D₀ and ⁵D₀ → ⁷F₄ and luminescence quantum yield of 58%, but the sample functionalized with a mixture monomers showed an increase in intensity on transition ⁵D₀ → ⁷F₂ and quantum yield of 67%.

Abstract: This work evaluated the use of chitosan as a biomolecule to functionalize the ZnAl_1.9Eu_0.1O₄/SiO₂ nanoparticles with 3:1 w/w chitosan to nanoparticles. ZnAl_1.9Eu_0.1O₄ nanoparticles were obtained by combustion reaction and silanized with 3-aminopropyltriethoxysilane. After silanized chitosan were added to the diluted in 1% acetic acid. The materials were centrifuged and placed in an oven at 60 °C for solvent evaporation. ZnAl_1.9Eu_0.1O₄ nanoparticles silanized had a ZnAl₂O₄ major phase and second phase EuAlO₃. After functionalized ZnAl_1.9Eu_0.1O₄ nanoparticles showed characteristic crystalline phase of spinel and chitosan. The FTIR spectrum showed absorption bands characteristic of C=O, axial deformation of - CN and Si-O bands from the silane agent. By analysis SEM, observed in the chitosan impregnated particles of approximately spherical form, containing amorphous and crystalline phases, with smaller particles and larger 5μm. The higher mass loss was 88.3% observed for the functionalized chitosan nanoparticles.

Abstract: Currently researchers has pointed chitosan as one of the viable alternatives for application as scaffolds in tissue regeneration, mainly due to its availability, biocompatibility, biodegradability and ability to chemical modifications, among them, the crosslinking. With the growing number of investigations of crosslinking agents from natural sources and its applicability, this work focuses on the development and microstructural characterization of chitosan scaffolds and chitosan crosslinked with genipina using the technique of freeze drying. Solutions were prepared with chitosan concentration of 2% (w / t), and genipin 0.15% (w / t) and 0.3% (w / t). These were frozen at-20 ° C and ≈ 196 ° C, and lyophilized. The effect of different concentrations of genipin and freezing rates of the solutions in the porous architecture of the scaffolds were evaluated by Scanning Electron Microscopy (SEM), Optical Digital Microscopy 2D and 3D (OM) and testing the Degree of Swelling (DS). The SEM analysis revealed the formation of a three dimensional structure with pores and / or channels interconnected, influenced by the freezing rate and addition of crosslinking agent, these variables also influence the absorption capacity of the scaffolds. It was observed by OM, the effectiveness of the crosslinking with genipin, through points of fluorescence presented.

Abstract: Tissue injuries are the main factors that lead to treatment by skin culture. In cases where the damage is extensive patient has insufficient amount of tissue to recover the area lost. A possible solution is the use of tissue engineering. Dermal substitutes must provide features and functions as close as possible to the normal skin. The acellular dermis can be obtained from the own patient and represents a viable alternative as a graft. The acellular dermis is used as a dermal analogue to the implantation of cells for tissue engineering treatment. The aim of this study was to compare different ways of obtaining mouse skin acellular dermis and characterize this dermis by macroscopic visualization, light and atomic force microscopy and cell culture.

Abstract: The study deals with the direct manufacturing of hydroxyapatite scaffolds using selective polymerization of the slurry liquid phase. The bovine hydroxyapatite has great similarity with the human bone structure, making it able for a direct connection with the bone tissues. This study aims to obtain scaffolds using a new technique of rapid prototyping, obtained by polymerization of acrylic resin (liquid phase of slurry) by ultraviolet light present in a range of the band spectrum emitted by the blue laser light. Sub-micrometer hydroxyapatite was obtained by the calcination and grinding of bovine bone in a vibratory mill. Mixtures of hydroxyapatite and resin were prototyped in three-dimensional pieces and sintered afterword and subjected to blue laser emission path directed in a CNC equipment. Grounded particles obtained in the grinding vibratory mill, with equivalent diameter of 0.35 microns, were reactive enough to compensate the low green densification bellow 50 vol%. Polymerization tests realized indicated that the incidence of the laser with fluency of 170 mW.s/mm² promoted the curing of the 0.5 mm diameter pieces in depth about 0.5 mm, which allowed the prototyping of the scaffolds with sufficient mechanical strength for handling.

Abstract: The process of aluminum anodizing forms an oxide layer constituted of nanotubes where it is possible to insert compounds, amongst these are the pigments and dyes. This study has as its main aim to study the behavior of aluminum alloy 6000, anodized and dyed with monolite red in Na₂SO₄ 0.5 mol L^-1 and pH = 4. The techniques employed were: anodic potentiostatic polarization, open circuit potential, chemometry, polarization resistance and optical micrograph. The factorial planning was proposed using four variables (anodizing time, current density, electrolyte concentration, and dye), the response to the planning was the charge transfer resistance. Polarization curves revealed that the anodized and dyed aluminum samples are much more resistant than the non-anodized aluminum. Optical microscopy analyses demonstrated that the dissolution of dye occurs in the solution, but not enough to break the film. As the main result, efficient coloring of aluminum parts was verified with reduction in costs in relation to the energy employed in the process, associated to reduction in time spent for the anodizing process, which makes it suitable to increase industrial production of dyed aluminum parts.

Abstract: Paint durability is directly linked to the efficiency of the substrate pre-treatment system. The objective to treat the carbon steel surface prior to painting is to turn the unstable metal surface into a stable surface one, an inert base to receive the paint. This is the main function of the phosphatization processes, which enables good paint adherence and prevents the development of corrosion processes. The demand for cleaner technologies, with lower residue generation, makes the phosphatization an unappealing method, and in this context the use of nanoceramics is an alternative to phosphate conversion layers. The objective of this study is to form a protection film which employs an organic molecule together with the zircon oxide, forming a layer which is able to anchor paint and increase the carbon steel resistance to corrosion. The treatment process conditions were established through the factorial planning, and the samples evaluated through the electrochemical impedance spectroscopy, scanning electronic microscopy and energy dispersive analysis. After comparing results of the electrochemical evaluation of the coating proposed with the iron and zinc phosphate coatings, it was possible to see that the film formed presented better corrosion resistance properties.

Abstract: Polyolefins are increasingly used in the construction of lightweight structures. Due to their low surface energy, it is difficult to have a proper bond with adhesives and paints. By using cold plasma treatments, these surfaces can be activated through the formation of highly reactive functional groups that can promote high strength adhesive bonds. This paper compares the results of cold plasma treatments using two techniques (low pressure and atmospheric plasma torch) applied on polypropylene and high density polyethylene. The obtained data allow the demonstration of a higher effectiveness of atmospheric plasma, with a significant increase in surface energy in both materials.

Abstract: The use of intrinsically conductive polymers such as polyaniline (PAni) has been presented as an alternative protective coating against corrosion, it intensifies the effect of anodic passivation and protection of the material. Given the difficulty in obtaining films of polyaniline in the oxidized form and driver in a self-supported and cohesive on the surface of metal substrates. Was held the undoped of the polymer, with the use of NH₄OH solution to passing the PAni oxidized state and non-conducting polyaniline emeraldine base known as PAni EB. The complete mixture of PAni EB, organic solvent and plasticizer 4-chloro-3-methylphenol, allowed to obtain a resin. This was applied in AISI 1006 steel plates with the aid equipment Spin Coater. The film was characterized by thermal analysis TGA, where it was found that the coating is the result of the reaction components, predominantly the structure of PAni EB. The electrochemical tests of Cyclic Voltammetry and Potential Open Circuit were carried out in 2 molL^-1 H₂SO₄ solution, which indicated the formation of redox couple polymer-metal, which provides the formation of passivating oxides, which allow the metal anodic protection against corrosion.

Abstract: Carbon steel is widely employed in the production of parts and machinery which supply the most diverse industrial sectors, such as the production of domestic appliances and cars. However, it presents low chemical resistance, being necessary the superficial treatment with anti-corrosion substances. Most conventional surface treatments present harmful components to the environment and to life in general, as for instance, nickel, which is used in the phosphatization processes. More recently, researchers have been pointing to surface treatments which employ nanoceramics as potential substitutes to phosphatization. This study aims to develop a nanoceramic treatment to the carbon steel 1008, based on self-assembling molecule (SAM) and titanium dioxide. Carbon steel samples were SAM treated and then immersed in a solution containing TiO₂. A chemometric study was developed to evaluate the best treatment conditions, using the software Designer Expert. For the electrochemical characterization, electrochemical impedance spectroscopy (EIS) tests were carried out. Results revealed that the SAM + TiO₂ coating presents higher resistance to polarization than the samples treated with zinc phosphate, in a 0.01 mol L^-1 sulphur acid medium.