Enhancing analytical capabilities at an affordable cost: A lab-made 3D-printed external reflection accessory for...

This work introduces a 3D-printed lab-made accessory designed for external reflectance measurements in the infrared spectrum. Integrated effectively with commercial spectrometers, the module provides adaptability, cost-effectiveness, sustainability, and ease of operation ensuring high-quality measurements for a variety of applications. Evaluating its performance, precise mirror alignment and an angle of incidence of 44.97° ± 0.032 were achieved. The module demonstrated strong capabilities in estimating optical constants of polymeric materials, including high density polyethylene (HDPE), polycarbonate (PC), and polystyrene (PS), exhibiting good agreement with literature values. This result was achieved by Kramers-Kronig analysis of the reflectance data, with a simple Python code, using the Numpy library. In addition, real-time in situ monitoring of the curing process of a commercial diglycidyl ether bisphenol A (DGEBA) epoxy resin was carried out from the absorptivity index spectrum computed for each instant of time. The data were fitted by the Kamal-Sourour kinetic model and the results showed good agreement with the current literature. Thus, the external reflection accessory is a valuable tool for capturing similar dynamic chemical processes using infrared spectroscopic analysis, being a simple, precise, non-sample-destructive, cost effective, and adaptable instrument for many analytical purposes. The designed module has potential applications in diverse analytical fields, enabling scientific research and industrial processes of interest.