Near-Infrared Reflectance for Silica Surface Area Determination in Aerospace Materials

The specific surface area of a filler influences its dispersion and interaction with the rubber and consequently the properties of thermal insulation in aerospace components. However, its determination generally requires complex instrumental methods. Therefore, the development of simpler methodologies with equivalent or higher precision remains of scientific interest. This study investigates the application of Fourier transform infrared spectroscopy using near-infrared (NIR) reflectance and the more conventional diffuse reflectance for silica analysis, a filler widely used in polymeric formulations. The analyzed samples presented surface area values between 170 and 800 m2·g-1. Results showed a methodological error within the instrumental limit (2%), lower than that reported for conventional methods (4-7%). The NIR reflectance methodology based on the relative band (A5260/A4540) provided the most accurate results and can be considered a practical alternative to conventional gas adsorption techniques, enabling shorter analysis times, a feature that is particularly relevant for aerospace processes subject to demanding project schedules.