Effects of Moisture and Fiber Type on Infrared Absorption of Fabrics

A study of variations in IR absorption characteristics of fabrics with moisture regain and fiber type is discussed. Infrared spectral absorptivities of fabrics are measured over the range of wavelengths from 0.7 to 25 microns. These values are used with the normalized emission characteristics of blackbody emitters to calculate average absorptivities for blackbody emitter temperatures ranging from 500 to 3000 K. Overall radiant efficiencies of the blackbody emitters are calculated by multiplying average absorptivities by the radiant efficiencies of emitters in converting input power to IR radiant output power. The absorption characteristics of several fabrics such as polypropylene and wool are measured so that the behavior of hydrophilic and hydrophobic fibers can be compared. Correlation equations are presented for average absorptivities of several fabrics as a function of moisture regain.