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.
Paints; PU; NC; NIR; MIR; UATR; DRIFT and measurement
