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Influence of the Orientation of Polypropylene Fibers on Their Radiative Properties

Volume 48, Number 4 (April 1994) Page 472-476

Papini, Marie

Radiative properties of fibers are wavelength and angular dependent. Cross sections of fibers depend on the direction of the incoming radiation. Measurements of the total and diffuse near-normal hemispherical spectral reflectances of polypropylene fibers over two wavelength ranges (0.25-2.5 μm and 2.5-15.5 μm) show that reflectance is higher when fibers are aligned parallel to the cell boundaries and lower when they are oriented perpendicular to the cell boundaries. The insulating property of the material is increased in the first case, and the radiative heat transfer is at a maximum in the second case. The effect of fiber diameter is also shown to give opposite variations for the two wavelength ranges.