Centro Tecnologico Do Exercito

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Centro Tecnologico Do Exercito

Brazil

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Ribeiro S.P.,Secao de Engineering Quimica | Santiago D.G.,Centro Tecnologico Do Exercito | Dos S. Vianna Jr. A.,University of Sao Paulo
Polimeros | Year: 2012

GAP is an aliphatic polyether that includes hydroxyl groups and highly energetic azide groups. Thus, it is an energetic material that can be used as binder or plasticizing agent in propellants and explosive mixtures. The glycidyl azide polymer (GAP) was synthesized and characterized by direct conversion of epichlorohydrin. GAP was synthesized by reaction of sodium azide, epichlorohydrin, and some extensor alcohols. The investigation focused on the effects of some key reaction parameters including reagent proportions, reaction time and two different solvents. The product was characterized by FTIR, UV, NMR, DSC, elemental analysis, TGA and GPC. The species were also evaluated through molecular weight (GPC), glass transition temperature (DSC), ignition time and sensitivity.


Cardoso D.R.,Centro Tecnologico do Exercito | Cardoso T.A.O.,Fundacao Oswaldo Cruz
Ciencia e Saude Coletiva | Year: 2011

Today, bioterrorism is a real threat in the whole world. Considering the actions of bioterrorism by using biological agents capable of promoting great epidemics and overload in the health systems of any city, state or country, the bioterrorism is not only a health professional concern, but government and military also. This article discusses a bibliographical review done in the LILACS, MEDLINE, SciELO and REPIDISCA databases, during the period of 1997 the 2007, the characteristics of related national publications to the bioterrorism, the type of biological agents studied, and the existing knowledge in the country to face a bioterrorism event, in order to feed with information the professionals who will act in first reply to the bioterrorism events and that are essential to reduce the number of victims.


Filho A.A.M.F.,Centro Tecnologico Do Exercito | Gomes A.D.S.,Federal University of Rio de Janeiro
International Journal of Polymeric Materials and Polymeric Biomaterials | Year: 2010

Sulfonated aromatic polymers generally show high swelling at high proton conductivity. This disadvantage makes many of them unfit for proton exchange membrane applications. Crosslinking of the polymer is one way to overcome this problem. In this study, radiation-induced crosslinking was performed on a sulfonated polysulfone membrane, with doses ranging from 2.5 to 25.0kGy (dose rate: 45Gy/min) using gamma rays from a 60Co source. The pristine sulfonated polysulfones was obtained by mild sulfonation of bisphenol-A-polysulfone with trimethylsilyl chlorosulfonate as sulfonating agent. The proton conductivity of the membranes was characterized by means of electrical impedance spectroscopy techniques. Ion-exchange capacity, degree of sulfonation, water content and chemical stability membrane properties were characterized before and after irradiation. The results show that the mechanical, chemical and thermal stability of the membrane improve after irradiation. The degree of sulfonation and the proton conductivity exhibit a tendency to decrease with increasing irradiation total dose.


Schettini A.R.A.,Centro Tecnologico Do Exercito | Khastgir D.,Indian Institute of Technology Kharagpur | Soares B.G.,Federal University of Rio de Janeiro
Polymer Engineering and Science | Year: 2012

Conducting composites of polyaniline doped with dodecylbenzenesulfonic acid (PAni.DBSA), carbon black (CB) and poly(styrene-b-styrene-butadiene-b-styrene) (STF) as supporting matrix were prepared by in situ polymerization. The influence of components and composition (% w/w) on the electromagnetic properties (dielectric constant ε and the dielectric loss ε) and electromagnetic interference shielding effectiveness (EMI-SE) of the materials were evaluated with a waveguide, using a microwave network analyzer from 8.2 to 12.4 GHz (X-band). It was found that CB presence generates adverse effects on PAni.DBSA yield during synthesis, as it can be seen by X-ray diffraction and TGA analyses. The type of PAni.DBSA formed modifies the composites properties. Dielectric constant, loss factor, and EMI shielding increase with conductive filler loading. Both the fillers, individually and in combination, increase the properties; however, the effect is not additive in nature. POLYM. ENG. SCI., 52:2041-2048, 2012. © 2012 Society of Plastics Engineers Copyright © 2012 Society of Plastics Engineers.


Schettini A.R.A.,Centro Tecnologico Do Exercito | Soares B.G.,Federal University of Rio de Janeiro
Macromolecular Symposia | Year: 2011

Conducting composites of polyaniline doped with dodecylbenzenesulfonic acid (PAni-DBSA) and poly(styrene-b-styrene-butadiene-b-styrene) (STF) as supporting matrix were prepared by in situ synthesis. The influence of composition and thickness on the electromagnetic properties and shielding effectiveness (SE) of the materials was evaluated using a microwave network analyzer and a standard rectangular waveguide from 8.2-12.4 GHz (X-band). It was found that the composition 49/51 exhibited the best SE and the higher values of reflected power (P R), ε′, ε″ and ε*. The compositions 12/88 and 17/83 presented the higher values of transmitted power (P T) and absorbed power (P A), respectively. The composition 25/75 presented the higher value of tan Î. The thickness of 5Ã - showed the best SE and higher value of P R. The higher value of transmitted power (P T) was obtained for thickness of 1Ã - . The values of P A were similar for all thicknesses. The thickness of 1x showed the higher values of ε′, ε″, ε* and tan Î. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


De Castro M.S.B.,Centro Tecnologico Do Exercito | Ferreira C.L.,Military Institute of Engineering of Rio de Janeiro | De Avillez R.R.,Pontifical Catholic University of Rio de Janeiro
Infrared Physics and Technology | Year: 2013

Vanadium oxide thin films were grown by RF magnetron sputtering from a V2O5 target at room temperature, an alternative route of production of vanadium oxide thin films for infrared detector applications. The films were deposited on glass substrates, in an argon-oxygen atmosphere with an oxygen partial pressure from nominal 0% to 20% of the total pressure. X-ray diffraction (XRD) and X-ray photon spectroscopy (XPS) analyses showed that the films were a mixture of several vanadium oxides (V2O5, VO2, V5O9 and V2O3), which resulted in different colors, from yellow to black, depending on composition. The electrical resistivity varied from 1 mΩ cm to more than 500 Ω cm and the thermal coefficient of resistance (TCR), varied from -0.02 to -2.51% K-1. Computational thermodynamics was used to simulate the phase diagram of the vanadium-oxygen system. Even if plasma processes are far from equilibrium, this diagram provides the range of oxygen pressures that lead to the growth of different vanadium oxide phases. These conditions were used in the present work. © 2013 Elsevier Ltd. All rights reserved.


Silva G.R.,Military Institute of Engineering of Rio de Janeiro | Borges Jr. I.,Military Institute of Engineering of Rio de Janeiro | Figueroa-Villar J.D.,Military Institute of Engineering of Rio de Janeiro | De Castro A.T.,Centro Tecnologico Do Exercito
Quimica Nova | Year: 2012

Chemical agents are substances used for their toxic effects on humans, animals and plants. The main objective of chemical defense is to develop systems that reduce these effects while minimizing impact on the operational capacity of military troops. In this work, a report on the development of chemical warfare agents since the First World War and their classification is presented. Special attention is given to neurotoxic agents, the most lethal group of chemical agents known to date.


Martins G.S.,Instituto Federal Of Minas Gerais Ifmgcongonhas | Pereira I.M.,Centro Tecnologico do Exercito | Hoehne N.M.,Federal University of Minas Gerais | Orefice R.L.,Federal University of Minas Gerais
Polymer Engineering and Science | Year: 2016

In this work, the effect of synthesizing shape memory polyurethanes in aqueous dispersions instead of in organic solvents on the structure and properties of the obtained polymers was investigated. Shape memory polyurethanes based on polycaprolactone diol and isophorone diisocyanate were synthesized by two routes: (1) aqueous dispersion (PU/SMWATER) and (2) dissolution in THF (PU/SMTHF). The samples were analyzed by infrared spectroscopy (FTIR), X-ray diffraction (XRD), static light scattering (SLS), atomic force microscopy (AFM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and mechanical tests. The aqueous dispersion method led to the production of polyurethanes with a higher degree of phase separation and a higher degree of crystallinity. The morphology of the obtained polyurethanes demonstrated that PU/SMWATER displays a structure with better defined phase separated domains. The polyurethanes exhibited similar average molar masses, soft segment glass transitions (Tgs) and mechanical properties. The lower degrees of phase separation and crystallinity of the PU/SMTHF led to lower values for the shape memory properties (shape recovery ratio (Rr)). The observed changes in the structure of the polyurethanes due to the replacement of organic solvent by an aqueous dispersion during their syntheses confirmed the preparation of shape memory polyurethanes with enhanced shape memory properties. © 2016 Society of Plastics Engineers © 2016 Society of Plastics Engineers.


Martins G.S.,Federal Institute Of Minas Gerais Ifmgav Professor Mario Werneck | Pereira I.M.,Centro Tecnologico do Exercito | Guerra Diniz A.E.,Federal University of Minas Gerais | Orefice R.L.,Federal University of Minas Gerais
Journal of Applied Polymer Science | Year: 2016

In this work, the idea of modulating the shape memory properties of polyurethanes by changing their macromolecular architecture through the incorporation of polystyrene-based moieties was investigated. To study these effects, poly(styrene-co-maleic anhydride) (SMA) was incorporated during the synthesis of PU as a potential chain extender. Two sample groups were produced: (i) PU, produced with hydrazine as a chain extender and (ii) PUSMA, produced with the addition of SMA instead of hydrazine. The results suggest that the SMA incorporation in the PUSMA chains occurred by the reaction between NCO groups of the PU and maleic anhydride (MA) of the SMA. The presence of SMA was useful in modulating the structure of PU by reducing the soft segment crystallinity and molar mass. These changes in the structure and macromolecular architecture due to the presence of SMA moieties in PU chains led to pronounced improvements in strength, toughness, and the shape recovery ratio. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44471. © 2016 Wiley Periodicals, Inc.


Almeida R.T.,Centro Tecnologico do Exercito
18th Saint Petersburg International Conference on Integrated Navigation Systems, ICINS 2011 - Proceedings | Year: 2011

Monolithic Micro-Optic Gyroscopes (MMOC), device maybe a candidate to replace the Fiber-Optic Gyroscopes (FOG) due to the fact it can present the same advantages of manufacture and portability from the micro machined devices at a minimum cost, with no mechanics parts or all solid-state. The effort of subject consists in a development of micro-optic waveguides in a micro-ring configuration set single connected in a principal ring, working as optic resonators, forming a Single Coupled Integrated Spaced Sequence of Optic Resonators Structure (Single CISSORS), to detecting and measuring the phase variation of optical signal due to the Sagnac effect. in the highly compact rotation sensors with high performance and low cost. Such investigation resides in the electro-optic integrated structures or EOIC (Electro-Optic Integrated Circuits) building possibility, based in doped optical polymers, like the Polymethil Metacrylate, instead of electro-optic crystals like of the LiNbO3 and the TiO2 due to the handling difficulties, as well the nonflexibility of its intrinsic parameters changing, that implies in an elevated dependence degree of sensor's geometry due to those parameters, that can be very easy using optical polymers like the PMMA that presents handling facilitates of its intrinsic parameters changing. In fact, it offers a low dielectric permissivity and a great second order nonlinear coefficient r33 (or Pockels coefficient) compared with the crystals. The r33 coefficient can be obtained by poling process. The value of 100pm/V or above of r33 (against LiTaO5, such r33 constant is 33pm/V) value constant was reported. It allows operations at the range above hundreds of GHz. Another advantages resides also in the fact of this element presents index of refraction in the range of 1, 50 to 1, 48 at range of 440nm to 1100nm wavelength, adjusted chemically by fluorinating process during the perform manufacturing, whereas the crystals present this index in the range of 2, 154 to 2, 28968 in the same range of wavelength. The PMMA, for instance, is less dispersive than the crystals.

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