“…In addition, when testing thin films, the molecular absorption coefficients in near-infrared are quite small, requiring a larger sample volume to obtain an unintended signal. [157][158][159][160][161][162][163][164][165][166] The basic analysis of the reflectivity suitability of NIR spectroscopy for on-line monitoring of the conversion rate of very thin, both transparent and pigment-containing, acrylate coatings on various substrates (i.e., PP film, paper, wood, MDF) was performed by Scherzer et al 30,167,168,311 This technique can be successfully used to monitor the conversion of double acrylate bonds in thin layers around a few μm under UV exposure, both on a laboratory scale and on a semi-technical coating line. [169][170][171] In addition, a very good linear correlation has been found between the results of the NIR technique and those of the FTIR spectroscopy and the HPLC technique for the determination of monomer conversions, although chromatographic methods show higher conversion values than spectroscopic methods.…”