A Novel Approach in Simulation of Spectral Reflectance of Nanopigment Coated Fabrics

Coating of fabrics with spectrally selective nanopigments, in order to manipulate their optical properties, has been introduced in recent years. This method presents a new field in high performance textiles which covers high technological aspects such as UV protective fabrics, Solar cells and cool fabrics as well. One of the most important approaches in prediction of reflectance factor of coated fabrics is based on Discrete Ordinate Method (DOM), namely, Kubelka-Munk or Multi Flux Model, where the fabric is considered as a continuous medium consists of a dispersion of nanopigments. However, ignored surface scattering on interfaces causes considerable error. Geometric optic, on the other hand, is utilized widely for prediction of spectral behavior of particles with very large dimension compared with incident wavelength. The model lacks limitation of DOM but is not appropriate for nanopigments of small diameters. According to the fact that, coated fabrics are systems consists of nano and micron sized materials, a theoretical model is proposed in which radiative properties of micro particles are described using Geometric Optic, and those for nano and submicron sized particles are described using Mie scattering theory. Subsequently, the experimental realization of proposed model has been conducted on Titanium dioxide nanopigments coated on polyester fabrics, and the successful comparison of the proposed model with experimental results confirms its suitability, and introduces a rather new procedure in the field of radiation transfer through mixed beds of elements with extremely different sizes.