Materials Science Forum Vol. 1012

Abstract: The β-titanium alloys have properties such as low elastic modulus associated with good properties mechanical, higher corrosion resistance and biocompatibility properties ideal for orthopedic application. Recent studies showed that the traditional Ti–6Al–4V alloy (α+β type) presented biological toxicity due to the presence of Al and V in its composition. In this scenario the present work aims at the fabrication and characterization of the microstructure and the mechanical properties of the as–cast Ti-12Mo-25Nb alloy. This alloy was produced by arc melting with non-consumable tungsten electrode in argon atmosphere. The material was characterized by X–ray diffraction, optical microscopy, Vickers hardness and elastic modulus by impulse excitation. The results of the microstructural characterization showed the presence of the β single phase, hardness equal to 207HV and the elastic modulus equal to 77GPa. These characteristics shows that this alloy is suitable for biomedical application such as implants.

Abstract: Fractures resulting from wear and fatigue process have been identified as the main causes of failure in biomaterials, especially in implants that act in place of bone or other hard tissue, as they are subject to conditions involving severe cyclic loadings. In biomaterialscase, the types of failures mentioned above must also be evaluated under the effect of degradation or corrosion, due to the direct contact with body fluids. The present research analyzed the fatigue induced by corrosion fracture of an orthopaedic implant for total knee replacementproduced with an austenitic ASTM F138 stainless steel. The morphology, compositions of the interfaces and subsequent corrosive pitting were characterized by stereoscopy and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). Stress concentration, inclusions and high carbon levels were the main reasons of failure.

Abstract: The use of dental implants of titanium and its alloys has proved to be effective, through well established and documented parameters, both in the dimensions and in the manufacturing processes and also in the surgical techniques. There are clinical situations where there is a need to reduce the diameter of the implants, below 3.75 mm in diameter. In the current state of art of the implant technology it is desirable that these also have surfaces capable of decreasing the period of osseointegration. In the present work, to improve the mechanical strength of the material, an alloy of 80% of Ti and 20% of Zr % in mass was proposed and elaborated, aiming its use as biomaterial. Physical, chemical, microstructural and mechanical characterization was carried out. The surfaces of the treated samples were observed using: scanning electron microscopy (SEM); semi quantitatively chemically analyzed using dispersive energy spectroscopy (EDS: wettability of the samples was determined and, finally, the roughness was measured using optical profilometry. For the conditions used in the present work, it was concluded, that the best surface treatment for the TiZr 80/20 alloy was acid etching with 1% vol. hydrofluoric acid for 5 minutes, as this treatment presented the most prominent results of wettability and roughness simultaneously.

Abstract: In this work, it was proposed to study the feasibility of biodiesel production, from residues of vegetable oils used in domestic activities, employing (CaCO₃) shells prepared like calcium oxide (CaO) as catalysts, in a batch reaction unit, on bench scale, installed at IPEN-CNEN/SP. This unit is capable of operating with high pressure hydrogen gas (up to 200bar) and high temperature (up to 500°C, using microwave - MW (2.450MHz, with up to 2kW continuous and 8kW pulsed) and conventional heating – (electric) MC. In the tests, the oil load (mL), type and mass of catalyst, with or without hydrogen gas pressure (bar), temperature (°C), reaction time (h), microwave power (W), the speed of the load (rpm) agitation and the conventional heating were evaluated. The analytical determinations of the samples were carried out by means of density, gas chromatography (GC) and X-ray fluorescence. Data were collected in order to be compared with other methodologies, already used in the literature. The purpose of this work was to analyze the efficiency of the use of these types of catalysts and oils in the production of biodiesel, as an alternative technology. The Ca and CaO contents found in the pink shell, before and after the calcination, were 36.2% and 98.8%, respectively. The best result obtained for the density was 0.875182g/cm³, for the test with 4g of calcined shell catalyst and reaction of 1h. As to the methyl ester content, the highest result was 95.33%, in a test with 4g of catalyst and reaction of 3h. In the non-calcined shell test (22.5g), although the amount of mass used was much larger (5% of the oil mass), the ester content was very low, 2.11%.

Abstract: Eucalyptus bark is an agroindustry residue generated in large quantities due to its physical-chemical characteristics. Several industries, such as the pulp and paper industry, the timber and derived industries, do the wood separation and commonly the bark is discarded in the field or sent to companies that consume them as an energy product. Although it is a material with a high energy content, even larger than the wood itself, due to its characteristics, some companies cannot consume this material without first processing it. This processing serves to change the geometry of the material, either by reducing the size of the fibers, that is to standardize a particle size, to facilitate the transport and internal logistics of the companies, until the arrival in the burners and / or boilers. Therefore, it is necessary to know some physical and chemical characteristics of the material before and after these changes. The purpose of this work was to characterize and compare the particulate matter with the processed material. It was carried out the immediate chemical analysis, the verification of the humidity and density, the calorific value of the materials and the thermal degradation in inert and oxidizing atmosphere. The results showed that there were beneficial changes in the characteristics of the materials, mainly in the thermal analyzes. These characteristics corroborate with the need to process the material in order to obtain better results in its applications.

Abstract: The manufacturing processes of polymeric implants for controlled drug release suggest a promising perspective of use for chemotherapeutic treatments. The objective of this study was to carry out a bibliographical survey of the last 10 years with experimental works to draw up a profile of methodologies and results achieved in this area. The literature search revealed 739 references, of which 19 were selected. The manufacturing by extrusion and injection are the most used. Regarding geographical distribution, Brazil occupies the 2nd place in the general list. The analysis of the literature on controlled release techniques of chemotherapeutic drugs demonstrates the scarce production in this area. It would be of great interest to have more studies on this topic, since it would be an alternative in the chemotherapeutic treatment.

Abstract: Miniemulsion polymerization process is a very versatile technique used for the polymeric encapsulation of the many essential oils. In this process some surfactant compounds are used to define the capsules characteristics, as an example the Sodium Lauryl Sulphate (SLS) that is one of the most used surfactants. But, after the miniemulsion polymerization synthesis the residual amount of SLS can manifest an antimicrobial action that can improve or to prejudice the final properties of the encapsulated products, depending of its percentual concentrations. In this sense, the objective of this work was to evaluate the antimicrobial activity of polycaprolactone (PCL) capsules synthesized with different residual concentrations of the SLS surfactant after the miniemulsion polymerization processes. The antimicrobial evaluations demonstrated from solid media diffusion test that the PCL microcapsules are microbiologically inactive for the bacteria Staphylococcus aureus and Escherichia coli when are synthetized with residual concentrations of SLS below 0.0125%. The minimum inhibitory concentration (MIC) of residual SLS for the bacteria Staphylococcus aureus is 0.0146% and for the bacteria Escherichia coli the complete bacterial inhibition not was detected at the maximum residual concentration studied of 0.1167%.

Abstract: With the increasing quality of life, the growing advancement of medicine and thus greater longevity of the population, the need for the development of biomaterials becomes increasingly necessary. Titanium alloys are widely used for biomedical application because they have corrosion resistance, biocompatibility, high hardness and low elasticity modulus compared to other metallic biomaterials. In the market, the titanium alloy most used for orthopedic purposes is the Ti-6Al-4V that despite its good mechanical and structural properties, present cytotoxic elements related to the presence of Al and V, pointing out the need for the development of new materials. In the current scenario, the most outstanding alloys are β Titanium alloys, which stand out due to their low elasticity modulus, which allows a high hardness/modulus ratio. Therefore, the objective of this work was to develop new studies on the Ti-12Mo-30Nb alloy, looking for good mechanical and structural characteristics and not cytotoxicity. Therefore, this alloy was produced by arc fusion with non-consumable tungsten electrode in an argon inert atmosphere. The material was characterized by X-ray Diffraction, Scanning Electron Microscopy, Vickers Hardness and Ultrasonic Elasticity Module. According to the results, it was verified that the alloy presented only the phase β in the microstructure and a hardness/modulus ratio superior to commercial alloy.