title: Qualitative and quantitative analysis of calcium-based microfillers using terahertz spectroscopy and imaging.
abstract: In different industrial applications, several strictly defined parameters of calcium-based microfillers such as average particle size, particle size distribution, morphology, specific surface area, polymorphism and chemical purity, play a key role in the determination of its usefulness and effectiveness. Therefore, an analytical tool is required for rapid and non-destructive characterization of calcium-based microfillers during the synthesis process or before its use in a further manufacturing process. Since spectroscopic techniques are preferred over microscopy and thermogravimetry, particularly due to its non-destructive nature and short analysis time, we applied terahertz (THz) spectroscopy to analyse calcite microfillers concentration in polymer matrix, its granulation and chemical treatment. Based on the analysis of peak absorbance amplitude, peak frequency position, and the appearance of additional spectral features, quantitative and qualitative analysis was successfully achieved. In addition, THz imaging was also applied for both quantitative and qualitative analysis of calcium-based microfillers. By using spatial distribution map, the inhomogeneity in concentration of calcium carbonate in polymer matrix was characterized. Moreover, by THz spectroscopy and imaging different calcium compounds were detected in binary mixtures. Finally, we demonstrated that the applied spectroscopic technique offers valuable results and can be, in combination with other spectroscopic and microscopic techniques, converted to a powerful rapid analytical tool.
authors.affiliation: Jožef Stefan International Postgraduate School, Jamova 39, SI-1000 Ljubljana, Slovenia. Electronic address: andreja.abina@mps.si.
authors.forename: Andreja
authors.initials: A
authors.lastname: Abina
authors.affiliation: Jožef Stefan International Postgraduate School, Jamova 39, SI-1000 Ljubljana, Slovenia; Faculty of Electrical Engineering, University of Ljubljana, Tržaška cesta 25, SI-1000 Ljubljana, Slovenia.
authors.forename: Uroš
authors.initials: U
authors.lastname: Puc
authors.affiliation: Jožef Stefan International Postgraduate School, Jamova 39, SI-1000 Ljubljana, Slovenia; Faculty of Electrical Engineering, University of Ljubljana, Tržaška cesta 25, SI-1000 Ljubljana, Slovenia.
authors.forename: Anton
authors.initials: A
authors.lastname: Jeglič
authors.affiliation: Calcit d.o.o, Stahovica 15, SI-1242 Stahovica, Slovenia.
authors.forename: Jana
authors.initials: J
authors.lastname: Prah
authors.affiliation: Optoelectronics Department, Center for Physical Sciences and Technology, LT-01108 Vilnius, Lithuania.
authors.forename: Rimvydas
authors.initials: R
authors.lastname: Venckevičius
authors.affiliation: Optoelectronics Department, Center for Physical Sciences and Technology, LT-01108 Vilnius, Lithuania.
authors.forename: Irmantas
authors.initials: I
authors.lastname: Kašalynas
authors.affiliation: Optoelectronics Department, Center for Physical Sciences and Technology, LT-01108 Vilnius, Lithuania.
authors.forename: Gintaras
authors.initials: G
authors.lastname: Valušis
authors.affiliation: Jožef Stefan International Postgraduate School, Jamova 39, SI-1000 Ljubljana, Slovenia; Department of Condensed Matter Physics, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia; Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška cesta 160, SI-2000 Maribor, Slovenia. Electronic address: aleksander.zidansek@ijs.si.
authors.forename: Aleksander
authors.initials: A
authors.lastname: Zidanšek
keywords: Calcium-based microfillers; Granulation; Surface treatment; Terahertz pulsed imaging; Terahertz time-domain spectroscopy