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Gregorutti R.W.,Laboratorio Of Entrenamiento Multidisciplinario Para La Investigacion Tecnologica | Grau J.E.,Laboratorio Of Entrenamiento Multidisciplinario Para La Investigacion Tecnologica | Sives F.,CONICET | Elsner C.I.,Research Center sarrollo En Tecnologia Of Pinturas | Elsner C.I.,National University of La Plata
Materials Science and Technology (United Kingdom) | Year: 2015

Mechanical, electrochemical and magnetic properties of duplex stainless steel were analysed to evaluate its use as biomaterial, comparing the results with those obtained for austenitic stainless steel. Yield and ultimate tensile strengths are almost twice in duplex stainless steel, being the values 870 MPa and 564 MPa, respectively. The electrochemical test revealed that this material has lower susceptibility to localised corrosion because of its greater passive range, 1 V from the open circuit potential, while the austenitic stainless steel exhibited a passive region of 0.370 V. Both steels behave as soft magnetic materials, however, duplex stainless steel has higher magnetic saturation and remanence, while austenitic stainless steel is more prone to heating when exposed to a magnetic field. © 2016 Institute of Materials, Minerals and Mining.


Canosa G.,National University of Costa Rica | Alfieri P.V.,National University of Costa Rica | Giudice C.A.,National University of Costa Rica | Giudice C.A.,Research Center sarrollo En Tecnologia Of Pinturas
Journal of Fire Sciences | Year: 2011

Aqueous solutions of nano lithium silicates with 5.5/1.0 and 7.5/1.0 silica/alkali molar ratios were used to impregnate Pinus radiata. To obtain these impregnants, a solution of 3.5/1.0 SiO2/Li2O molar ratio was used; this ratio was increased with nanosilica solution. The impregnations were realized using Bethell process. The curing was made with dibutylamine phosphate, a divalent cation and both chemicals used sequentially. Panels were tested in oxygen index (OI) chamber and two-foot tunnel. The statistical interpretation indicates that the best economical and technical performance was reached with impregnant of the highest silica content and with zinc cation for curing. © 2011 The Author(s).


Gregorutti R.W.,Laboratorio Of Entrenamiento Multidisciplinario Para La Investigacion Tecnologica | Grau J.E.,Laboratorio Of Entrenamiento Multidisciplinario Para La Investigacion Tecnologica | Elsner C.I.,Research Center sarrollo En Tecnologia Of Pinturas | Elsner C.I.,National University of La Plata
Materials Science and Technology (United Kingdom) | Year: 2012

Countergravity low pressure casting (CLA) was performed to enhance the properties of ASTMF745 stainless steel (SS), which is usually used as biomaterial. The macro- and microstructureswere compared with those obtained by the conventional process of investment casting (IC). TheSS cast by CLA (SSCLA) exhibited a smaller size of solidification cell and finer dendriticmicrostructure. The average of its dendritic primary spacing was 110·4 mm, while for the same steel cast by IC (SSIC), it was 186·7 μm. The density of non-metallic inclusions δ in the SSCLA was 717 I mm -2, being the majority of them smaller than 1·5 mm. In the case of SSIC, dI was 852 I mm -2, with a size distribution of up to 8 μm. The SSCLA showed a higher breakdown potential than the SSIC, the values being 0·p300 and 0·210 V(saturated calomel electrode) respectively, which means a higher resistance to suffer localised corrosion. Finely, the CLA process also allowed obtaining better mechanical properties. © 2012 Institute of Materials, Minerals and Mining.


Pardini F.M.,Research Center sarrollo En Tecnologia Of Pinturas | Amalvy J.I.,Research Center sarrollo En Tecnologia Of Pinturas | Amalvy J.I.,Institute Investigaciones Fisicoquimicas Teoricas y Aplicadas | Amalvy J.I.,National University of La Plata | Amalvy J.I.,National University of Costa Rica
Journal of Applied Polymer Science | Year: 2014

Polyurethane (PU)/poly[2-(diethylamino)ethyl methacrylate] hybrids, having a chemical bond between the PU and acrylic moieties and with different compositions, were prepared by the dispersion polymerization of 2-(diethylamino)ethyl methacrylate (DEA) in the presence of preformed PU chains with polymerizable terminal vinyl groups. The PU dispersion was synthesized according to a prepolymer mixing process by the polyaddition of isophorone diisocyanate, poly(propylene glycol), 2-hydroxyethyl methacrylate, and dimethylol propionic acid (DMPA). Then, it was dispersed in water by the prior neutralization of the carboxylic acid groups of DMPA with triethylamine, chain-extended with ethylenediamine. The effect of the DEA content on the swelling properties (water uptake and dynamic swelling degree) at different pHs and at 37°C was determined. The samples were also characterized by Fourier transform infrared spectroscopy and modulated differential scanning calorimetry. The experimental results indicate a higher water uptake when the DEA content was increased on the hybrid materials and a significant change in the kinetics of swelling at pH 4 compared to those at pH 7. The water content of the hydrogels depended on the DEA content, and it was inversely proportional to the pH value. The pure PU film did not show important changes over the pH range examined in this study. The synthesized hybrids were useful as drug-delivery, pH-sensitive matrices. © 2013 Wiley Periodicals, Inc.


Garcia M.T.,Research Center sarrollo En Tecnologia Of Pinturas | Perez M.C.,Research Center sarrollo En Tecnologia Of Pinturas | Perez M.C.,National University of La Plata | Stupak M.E.,Research Center sarrollo En Tecnologia Of Pinturas | And 2 more authors.
Revista Materia | Year: 2015

Biofouling leads to deterioration of any submerged material. The most widespread method for control is the application of cuprous oxide antifouling paints which are toxic. For this reason non-toxic natural products could be combined with small amounts of copper to diminish its contribution to the environment. Thymol is isolated from essential oils of several plants (thyme, oregano, basil) and it is well known for its antimicrobial properties. The hypothesis proposed in this study is this compound would inhibit initial steps in fouling sequence and consequently would also inhibit settlement of later species. The aim of this work was to reduce the amount of copper in antifouling paints employing thymol as an additive. Two antifouling paints were prepared, one containing 16[%] v/v copper and another with 1.6[%] copper + 2[%] thymol. Paints were applied on acrylic panels and were submerged in Mar del Plata harbor. After 6 months of immersion in Mar del Plata harbor fouling cover percentage on panels was estimated under stereomicroscope and optic microscope. Estimation of fouling cover by species was carried out using a 25 random point grid. Also, control paints and unpainted acrylic tiles were simultaneously submerged. All tests were performed in triplicate. Paints containing 1.6[%] copper + thymol and 16[%] copper were effective. No significance differences were registered in cover percentage between copper-based paints and copper+thymol based paints (p>0.05). Although these formulations showed a similar performance, copper+thymol based paint contains 90[%] lesser copper than a traditional copper based formulation. Then, the aim of this work was reached. © 2015 Universidade Federal do Rio de Janeiro. All rights reserved.

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