ABSTRACT
The main objective of this article is to provide the spectroscopic radiative properties of black poly(methyl methacrylate) (PMMA) including transmissivity, absorption coefficient, and complex index of refraction. To perform the required spectroscopy, four ultra-thin samples with thicknesses of 33 ± 1.3 , 50 ± 1.3 , 65 ± 1.0 , and 73 ± 1.5 µm were prepared. Then, by using UV-Vis-NIR and FTIR spectrometers, the spectrum of transmissivity was measured for the wavelength regions of 0.25 to 2.5 and 2.5 to 25 µm, respectively. Applying modified Beer's law, the absorption coefficient of black PMMA was extracted. To obtain the refractive index, first the reflectivity of the 6 mm sample of black PMMA measured by UV-Vis-NIR spectrometer. Then, applying the Kramers-Kronig transform and Fresnel relation, the refractive index of black PMMA was extracted. To investigate the effect of temperature on the absorbance of the material, ATR-FTIR spectroscopy was done for the temperatures below melting point (i.e., 160 ∘ C). Finally, a set of data for effective absorption coefficient as a function of depth from the sample surface and source temperature was proposed to be used in pyrolysis modeling.
