Polypropylene is considered as a representative thermoplastic matrix for advanced composite materials that have some advantages in various engineering applications. Wide-range infrared optical properties of polypropylene are important for combined heat transfer modeling in these composite materials, which are semitransparent in a considerable part of the whole spectral range. This study is focused on optical properties of polypropylene in the visible and near-infrared ranges because the measurements in these ranges exhibit a stronger effect of the processing temperature used in the material manufacturing. The experimental study is based on spectral measurements of both the normal-hemispherical reflectance and transmittance of polypropylene samples. The main characteristics of volumetric absorption and scattering are identified using the inverse problem solution based on the modified two-flux approximation, which is sufficiently accurate to determine the hemispherical characteristics of the radiation field in the range of the problem parameters. In particular, the effect of a relatively strong scattering is observed at the absorption peaks in the near-infrared range. An approximate theoretical model based on spectroscopic data is developed to estimate morphological changes arising in thermal processing of polypropylene at different temperatures.
© 2014 Optical Society of America
Original Manuscript: December 5, 2013
Revised Manuscript: March 21, 2014
Manuscript Accepted: March 24, 2014
Published: April 18, 2014
Vol. 9, Iss. 6 Virtual Journal for Biomedical Optics
Donia Hakoume, Leonid A. Dombrovsky, Didier Delaunay, and Benoit Rousseau, "Spectroscopic diagnostics of morphological changes arising in thermal processing of polypropylene," Appl. Opt. 53, 2702-2710 (2014)