ABSTRACT Ethylene propylene diene monomer rubber is used as flexible thermal protection for rocket engines, as well as in blends with polychloroprene, which can be applied in the aeronautical sector, and with great potential in the defense sector. However, there is not a considerable number of studies considering both polymers as a blend. In general, elastomer content quantification in blends is done by more complex instrumental methods. When performed by Fourier transform-infrared spectroscopy, the conventional transmission mode is used, usually without including the developed methodology error. Therefore, the Fourier transform infrared spectroscopy (FT-IR) methodology is proposed using the universal attenuated total reflection mode, with sample treatment (pyrolysis) to determine polychloroprene content in the mixture with ethylene propylene diene monomer. In accordance with the infrared spectrometer precision limits and rubber blends studies data found in the literature, the methodology error analysis shows a value close to 2%. In addition, it has the advantage of being a less complex methodology. This actual study uses a simple FT-IR analytical tool, scarce, especially for the rubber research community, to determine the content of rubber minor phase within the major phase. It is valuable in weapons reverse engineering, aiming at the knowledge of new thermal protections.

ABSTRACT Ethylene-propylene-diene elastomer (EPDM) is employed as thermal insulation for rocket motors, as well as EPDM blends with ethylene vinyl acetate (EVA) have been used in the aerospace industry. The quantification of these blends is more common using Fourier Transform Infrared Spectrometry (FT-IR) by transmission mode, but without discussing sample preparation and methodology error. Considering this fact, a methodology was developed for determining EVA content in binary blend with EPDM samples, by Universal Attenuated Total Reflection (UATR) technique, associated to thermogravimetric analysis (TGA). This last one, it was applied to determine Vinyl Acetate (VA) content in EVA and to identify differences between EPDM/EVA blends. Samples of the analyzed blends showed two VA contents and five proportions of EPDM/EVA: 90/10, 70/30, 50/50, 30/70, and 10/90. The carbonyl stretching vibration band C=O at 1740 cm-1 was used as analytical band in FT-IR quantification. Finally, the results presented excellent accuracy with a good linear correlation coefficient (R > 0.940) and with relative error values lower than 2%, respecting the precision limits of the FT-IR spectrometer.

ABSTRACT When some materials need to be characterized, the hydroxyl number (IOH) determination is especially useful, mainly for those applied in the aerospace field. Usually, this characterization is performed by wet chemistry, using methodologies involving several steps, such as derivatization. This is a time-consuming and costly step. On the other hand, when the analysis is performed by Fourier transform infrared (FT-IR) spectroscopy, the most used region is the medium infrared (MIR) and transmission techniques are usually employed. However, FT-IR methodology developed error is usually not discussed. FT-IR methodology was developed in near infrared (NIR) and MIR regions, including non-conventional techniques, such as universal attenuated total reflection (UATR) and transflectance (near infrared reflection accessory [NIRA]), and transmission, to determine IOH in surfactants, used in aerospace catalysts/cosmetic products, and polyesters, applied in paints. According to the samples’ characteristics, surfactants were analyzed by transmission/solution and, as received, by NIRA. Polyesters were analyzed by UATR and NIRA, as received. The IOH values for all samples were also measured by wet chemistry and/or potentiometry (supplier’s data) and used as reference. Good linear correlations were observed between 0.939 and 0.976, being considered with good precision, and between 88% (NIRA) and 98% (MIR) of the results were explained by developed methodologies.

Abstract The bicomponent fibers are a special class of fibers that consolidate two polymers in only one fiber in order to explore individual properties of each polymer and can be designed in a spatial configuration that allows the enhancement in application of this material. Thereby, an appropriate characterization of bicomponent fibers is very valuable to process monitoring, quality control and forensic investigation. The sheath-core bicomponent fiber composed by polyethylene (PE), polypropylene (PP) and titanium dioxide (TiO2) was analyzed by Fourier transform infrared (FT-IR) spectroscopy and other analytical methodologies. Results obtained by FT-IR using modern accessories showed efficiency to characterize the polymers of sheath (PE) and core (PP), moreover these polymers were confirmed by DSC (Differential Scanning Calorimetry). The morphology and elemental composition were also studied by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS). The thermogravimetric analysis (TGA) and colorimetric analysis allowed characterize and quantify the concentration of TiO2.

Abstract When using Fourier transform infrared spectroscopy (FT-IR) under the qualitative aspect for characterization of polymer blends, often a simple identification of each one of the existing polymers in the blend does not justify the material failure since different amounts of each component may result in different mechanical properties, which should be a possible cause for of material failure when applied to an automotive part. Thus, seeking for a better justification in the understanding of material failure analysis, a new quantitative FT-IR methodology was developed in the mid-infrared region (MIR), using the transmission techniques and universal attenuated reflectance for the determination of Acrylonitrile Butadiene Styrene (ABS) and polycarbonate (PC). Transmission mode was more suitable. The relative band (A831 /A2237) was chosen for the preparation of the calibration curve that showed a 0.99% error methodology, which is within the FT-IR spectrometer accuracy limit (≤ 2%); therefore, it is accurate for the analysis of the system.

Abstract The knowledge of the components that constitutes a rubber composition is important to justify the properties of the final device, particularly when it comes to elastomeric compositions used in the aerospace industry. The development of methodologies that can detect components, specially the smallest proportion of the rubbers composition is a constant challenge and an important gap in the studies of this nature. Therefore, methodologies by using standard techniques and/or of last generation are important in rubber industry and research laboratories, aiming application in related research. In this context, this study shows the coupling/association techniques (off-line) of thin layer chromatography and infrared spectroscopy (TLC/IR), being the IR spectra obtained by universal attenuated total reflection (UATR), applied to the analysis of additives in rubber compositions of ethylene-propylene-diene rubber (EPDM). Two EPDM compositions, a kind of eluent system and Gibbs' reagent, as developer, were used. Basically, all organic components were detected by this methodology, being possible to suggest that it can be applied for detecting additives of similar chemical structures, even though it's presents in small amounts in the composition.

ABSTRACT Fourier transform infrared spectroscopy techniques, associated or not to others, are a well-studied subject used for characterizing polymers/energetic materials that have been employed mainly in aerospace industries. However, the infrared analyses are usually qualitative and performed using the mid-infrared. This paper discusses the Fourier transform infrared spectroscopy qualitative and quantitative methodologies, coupled or not with thin layer chromatography and thermogravimetric analysis, for characterization of aerospace polymer systems, in some cases, using mid-infrared, near-infrared and far-infrared regions, by traditional accessories and the latest generation spectra mode, universal attenuated total reflection. This short review was made based on methodologies developed during the last two decades and published by many scientific and industrial research groups, emphasizing studies usually carried out in the last five years. A critical assessment and future trends were included.

Resumo Vários aditivos são incorporados nas formulações de tintas para evitar defeitos no revestimento e melhorar o desempenho nas aplicações, constituindo, desse modo, um sistema complexo. A caracterização de uma composição pode ser realizada por separações física/ química e técnicas analíticas instrumentais. A análise de multicomponentes é utilizada no estudo de não conformidades, investigação forense e pesquisa e desenvolvimento de novos produtos. As pesquisas correlatas, em geral, utilizam metodologias convencionais, encontrando algumas limitações, o que motiva a utilização de técnicas alternativas, incluindo acoplamentos, para a análise de aditivos em tintas. Nesse contexto, foi avaliada a aplicabilidade do acoplamento (indireto ou off-line) das técnicas de cromatografia de camada fina (TLC) e espectroscopia no infravermelho com transformada de Fourier (FT-IR), denominado TLC-IR, e extração seletiva na análise de aditivos em tinta à base de resina poliuretânica (PU) e nitrocelulose (NC). Foi utilizada uma formulação, avaliados três sistemas de eluentes e um tipo de revelador, o de Gibbs. Os espectros FT-IR foram obtidos por Reflexão Total Atenuada Universal (UATR). Os principais resultados mostraram que o plastificante Acetil Tributil Citrato (ATBC), aditivo majoritário, foi facilmente identificado por TLC-IR. A metodologia permitiu detectar e diferenciar plastificantes do tipo ftalato, como dioctil ftalato (DOP) e dibutil ftalato (DBP), mesmo em pequena quantidade de amostra, e identificar a oleamida (aditivo promotor de deslize) por meio de extração seletiva e UATR.

Abstract Various additives are incorporated into the paint formulations to prevent coating defects and improving the application performance, so it is a complex system. The characterization of the components present in this system can be performed by physical/ chemical separation and instrumental analytical techniques. Multi component analysis is used in the study of non-compliance, forensic investigation and research and development of new products. The related research generally uses conventional methodologies, finding some limitations, which motivates the use of alternative techniques, including couplings, for additive analysis in paints. In this context, has been reported the coupling (off-line) of thin layer chromatography (TLC) and Fourier transform infrared spectroscopy (FT-IR) (TLC-IR) and selective extraction in the analysis of additives in ink containing polyurethane (PU) and nitrocellulose (NC) resin. One formulation was evaluated, by using three eluting systems, and one type of developer, Gibbs. The FT-IR spectra were obtained by Universal Attenuated Total Reflection (UATR). The main results showed that the plasticizer Acetyl Tributyl Citrate (ATBC), as the majority additive was easily identified by TLC-IR. The methodology allowed even detect and differentiate phthalates like dioctyl phthalate (DOP) and dibutyl phthalate (DBP), even in small amount of sample, and identify oleamide (slip promoter) by means of selective extraction and UATR.

ABSTRACT: Iron oxide is a mineral compound that shows different polymorphic forms, including hematite (α-Fe2O3), magnetite (Fe3O4) and maghemite (γ-Fe2O3). Solid propulsion technology nanoparticulate materials, such as hematite and maghemite, exhibit high performance on thermal decomposition of ammonium perchlorate. The enhanced catalytic effect of metallic iron oxide nanoparticles is attributed to their particle size, more active sites and high surface area, which promotes more gas adsorption during thermal oxidation reactions. Nowadays, metallic iron nanoparticles can be synthesized via numerous methods, such as co-precipitation, sol-gel, microemulsion, or thermal decomposition. Although there are data on these synthetic methods in the literature, there is a lack of details related to nanoparticulate oxides and to their characterization techniques. In this context, this short review based on scientific papers, including data from the last two decades, presents methods for obtaining nanoparticulate iron oxides as well as the main aspects of the different characterization techniques and also about the decomposition aspects of these nanomaterials. Morphologies and structures of iron oxides can be characterized through transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy. As for textural properties, they are usually determined by physical adsorption techniques.

Foi desenvolvida uma metodologia para a determinação do teor de 5-etilideno 2-norboneno (ENB) em amostras de borracha (elastômero puro), à base do copolímero de etileno-propileno-dieno (EPDM), por espectroscopia no infravermelho com transformada de Fourier (FT-IR) de transmissão, sendo as amostras analisadas, após pirólise controlada e em bico de Bunsen. Embora ambas as técnicas tenham apresentado boa precisão, a realizada por pirólise em bico de Bunsen, com uso de banda e concentração relativa, mostrou-se mais adequada à determinação e ao uso em cálculos complementares de teores de ET e P.

A methodology was developed for determining the 5-ethylidene-2-norbornene (ENB) content in unvulcanized (pure elastomer) ethylene-propylene-diene (EPDM) elastomer, by transmission Fourier Transform infrared spectroscopy (FT-IR), after pyrolysis with and without temperature (T) control. Although both techniques have shown good accuracy, the pyrolysis without T control technique, with relative bands and concentrations, was more suitable for the ENB content determination and for the complementary calculations of ET and P.

Foi desenvolvida uma metodologia para a determinação dos teores de etileno (ET) e propileno (P) em amostras de borracha (elastômero puro, crua e vulcanizada), à base do copolímero de etileno-propileno-dieno monômero (EPDM), por espectroscopia no infravermelho com transformada de Fourier (FT-IR) de reflexão total atenuada universal (UATR) e de transmissão, sendo as amostras analisadas tal como recebidas ou após pirólise, respectivamente. Embora ambas as técnicas tenham apresentado boa precisão, com a análise UATR sendo mais adequada para o elastômero puro, a realizada por transmissão/pirólise mostrou-se mais adequada à análise de todos os tipos de EPDM (elastômero puro, crua e vulcanizada), podendo ser usada para formulações similares.

We developed a methodology for determining the concentration of ethylene and propylene in rubber samples (raw, unvulcanized or vulcanized) based on the copolymer of ethylene, propylene and diene monomer (EPDM) by Fourier transform infrared spectroscopy (FT-IR), using universal attenuated total reflection (UATR) and transmission techniques. Pristine and pyrolized samples were analyzed. Although both techniques have shown good accuracy, UATR is the most suitable for the pure elastomer and the transmission/pyrolysis technique is more suitable for the analysis of all types of EPDM (raw, unvulcanized or vulcanized) and can be used for similar formulations.

Técnicas FT-IR (UATR, PAS e MIC, com objetiva ATR) foram escolhidas para a caracterização da superfície da borracha de EPDM vulcanizada, após tratamento em plasma de Ar/O2 e N2/H2/Ar gerado em micro-ondas. Após tratamento, grupos oxigenados foram detectados por UATR e MIC/FT-IR, com objetiva ATR para as duas misturas gasosas, e possíveis grupos nitrogenados foram inseridos na superfície das amostras tratadas com plasma de N2/H2/Ar. A análise MIC/FT-IR sugeriu a formação de grupos em uma camada mais externa, para as amostras tratadas com plasma de N2/H2/Ar, sendo possível observar a redução na intensidade das bandas da absorção do CH2 e CH3, o que pode estar relacionado ao fato de o nitrogênio ser um gás menos permeável que o oxigênio. Diferentes velocidades, 0,05 cm.s-1 e 0,2 cm.s-1, foram utilizadas na análise PAS para avaliar a superfície após tratamento, e apenas para a velocidade 0,05 cm.s-1 com plasma de Ar/O2 alterações espectroscópicas foram detectadas. A redução na medida de ângulo de contato e o aumento na resistência ao descascamento da colagem indicaram melhoras nas propriedades adesivas da superfície. Falhas de adesão foram observadas entre a interface do filme de adesivo de PU e da borracha de EPDM, e confirmados por UATR/FT-IR.

The FT-IR techniques UATR, PAS and MIC with ATR objective were chosen to characterize the surface of EPDM rubber vulcanized after treatment in Ar/O2 or N2/H2/Ar plasma generated in a microwave oven. After treatment, oxygenated groups were detected by UATR and MIC-FT-IR, with ATR objective for the two gas mixtures, and possible nitrogenous groups were inserted on the surface after the plasma treatment with N2/H2/Ar. The MIC/FT-IR analysis suggested that groups were formed on an outermost layer, inferred from a reduced intensity of the CH2 and CH3 absorption bands for the treatment in N2/H2/Ar plasma, probably because nitrogen is less permeable than oxygen. Different speeds with PAS analyses (0.05 cm.s-1 and 0.2 cm.s-1) were used to evaluate the surface after treatment. Only for the speed 0.05 cm.s-1 in Ar/O2 plasma were spectroscopic changes detected. The decrease in the contact angle and the increased resistance to peel indicated improvements in the bonding adhesive properties of the surface. Bonding failure was observed between the adhesive PU film and the EPDM rubber, which was confirmed by UATR/FT-IR.

Foi elaborada uma nova metodologia nas regiões do infravermelho médio (MIR) e do infravermelho próximo (NIR), usando-se técnicas de Reflexão e/ou Transmissão para a determinação do teor de resina poliuretânica (PU) em misturas binárias com nitrocelulose (NC), utilizadas em formulações de tintas. A técnica de Reflexão Total Atenuada Universal (UATR) se mostrou útil na região MIR, para tal fim. Após a avaliação de diferentes bandas analíticas, de referência e de linhas de base, a banda relativa (A1541/ A1645) foi escolhida para a elaboração da curva de calibração, com erro de metodologia de 1,42%. As técnicas de Transmissão e Reflexão (DRIFT) foram utilizadas na região NIR (banda relativa A5902/ A5262) para validação, apresentando erros de metodologia de 1,42% e 1,60 %, respectivamente. Todos os erros relativos nas metodologias apresentaram-se dentro dos limites de precisão da análise quantitativa FT-IR, para as condições usadas (≤2%). A análise de amostras teste confirmou a precisão das metodologias desenvolvidas, que também apresentam praticidade, baixo custo e tempo reduzido de análise.

A new methodology was developed in the mid-infrared (MIR) and near infrared (NIR) regions by using techniques of Reflection and / or Transmission for the determination of polyurethane resin (PU) in binary mixtures with nitrocellulose (NC), used in paint formulations. The Universal Attenuated Total Reflection (UATR) technique proved useful in the MIR region for this purpose. From an evaluation of analytical bands and reference baselines, the relative band (A1541/A1645) was selected for the calibration curve, whose error was 1.42%. The Transmission and Reflection (DRIFT) techniques were used in the NIR region (relative band A5902 / A5262) for validation, and both showed good precision with an error of methodology of 1.42 and 1.60% respectively. All relative errors are within the accuracy of FT-IR quantitative analysis for the conditions used (² 2%). Analysis of test samples confirmed the accuracy of the methodologies, which also show practicality, low cost and reduced analysis time.