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 Rubber blends are important materials in automotive industry, as well as in other sectors. However, there are implications when suitable use of a polymer in an artifact is not made. In the automotive area, for example, the use of an elastomer without the fuel resistance requirement would result in component degradation, potential fuel leakage, and danger of fire. The use of polymer blends may be the solution to this problem. Fourier transform infrared spectroscopy (FT-IR) can be used for the knowledge of the polymer content of these blends. Then, FT-IR quantitative methodologies for determining acrylonitrile-butadiene copolymer (NBR) copolymer and butadiene-styrene copolymer (SBR) contents were developed by the transflectance accessory, NIRA, and the transmission mode, being the sample analyzed by transmission and universal attenuated total reflection (UATR) in the medium infrared (MIR). UATR and NIRA methodologies showed better accuracy. However, the MIR analysis showed a detection limit between 10-20% of NBR.

Abstract It is a well-established fact that rubber accelerator is essential to provide solution in different sectors. However, there is a reversal process which can reduce the material performance. Sulfur accelerators donors and organic peroxides have been presented as a solution to the problem. The methodology development that can separate or characterize those components is a challenge and still allows gaps, explained by the application of conventional technique to reach this goal. This study aimed at contributing to the use of off-line coupling of thin layer chromatography (TLC)/infrared spectroscopy (IR) by Universal Attenuated Total Reflection (UATR) for analysis of N-cyclohexyl-2-benzotiazolsulfenamide (CBS), tetraethylthiuram disulfide (TMTD) and dicumyl peroxide (DCP), in natural poly-cis-isoprene (NR) formulations, containing naphthenic oil. The best results were obtained for the plasticizer and DCP, in formulations that had a greater proportion of these compounds. The separation of CBS and TMTD was made with less effectiveness, due to bands overlapping.