Abstract Quantification of elastomer content for the ethylene-propylene diene monomer/polybutadiene blend are seldom subjects in the literature, mainly due to rubber compatibility problems. However, suitable blend contents can lead to desirable properties. Infrared spectroscopy can quantify this type of blend even if some bands overlap, which can be resolved with the proper choice of spectrum obtaining mode and non-overlapping analytical bands. This study evaluates the ethylene-propylene diene monomer/polybutadiene blend quantification by transmission, reflection and transflectance infrared. Even though all of the methodologies showed satisfactory results, transmission mode provided better accuracy. The methodology is simple and suited for the rubber industry. The sample with the higher BR content provided the best result. The band at 743 cm-1 is weak and results in even weaker absorptions when measuring samples with low BR content. On the other hand, the developed methodologies provided an accurate determination of low EPDM contents. For infrared spectroscopy researchers, these results not only encourage using different spectra obtaining modes application, including less conventional ones such as transflectance in the near infrared region for quantitative determination, it also contributes to a wide discussion of errors in the developed methodologies, which are also seldom discussed in publications.

Abstract Silica is a versatile material employed in different applications fields including aerospace, especially for rocket engines thermal protections. It is known that particles diameter causes variations in the material properties, and the best-known methods for diameter determination in general consist of several steps in sample preparation such as drying, sieving and the determination of the refractive index according different methods. On the other hand, Fourier transform infrared spectroscopy techniques (FT-IR), in reflectance mode, related to the particle size, are less used for this type of determination. Moreover, methodologies in the near infrared region (NIR) are even less explored. Therefore, the aim of this paper is to present a FTIR methodology for diffuse reflectance (DRIFT) in the middle infrared region (MIR) and reflectance analysis in near infrared region (NIRA) for the determination of the particle diameter on silica samples. Both methodologies showed good results. As proven by a test sample analysis, NIRA methodology indicated better precision. Furthermore, considering small and intermediated particle sizes, a tendency towards smaller errors for the absorbance measurements of the samples was found, consistently with the available literature results.