QUANTITATIVE PHOTOTHERMAL RADIOMETRIC AND FT-IR PHOTOACOUSTIC MEASUREMENTS OF SPECIALTY PAPERS

Frequency-domain laser infrared photothermal radiometry (PTR) and phot oacoustic Fourier transform spectroscopy (FT-IR/PAS) were used for the measurement of the thermophysical properties (thermal diffusivity, al pha, and conductivity, k) of specialty paper samples with various cott on contents. An improved one-dimensional photothermal model of a free- standing sheet of paper in air that includes both the transmission and backscattering mode was introduced. A high degree of accuracy and rel iability was obtained when a multiparameter-fit optimization algorithm was used to examine the transmission and backscattered PTR experiment al results. The ability to measure alpha and its variation, Delta alph a, as a result of the manufacturing process via the PTR technique is i nvaluable in terms of the quality control of paper products.