A New Simplified Model for Predicting the UV-Protective Properties of Monofilament PET Fabrics

Abstract

Knowing the reflection, transmission, and absorption properties of the yarns from which the woven fabric is made, prediction of a fabric’s UV-protective properties is simple. Using the geometrical properties of monofilament yarns and fabrics, which were determined optically, and following the cover factor theory, we have determined the areas of fabrics covered with no yarns, only one yarn, and two yarns. From a special selected set of high-module polyethylene terephthalate (PET) monofilament materials (e.g., fabrics), we have elaborated a method for determining the reflection, transmission, and absorption of yarns. By first defining the differently covered areas of fabrics, we were able to use them in a mathematical model for calculating and predicting the UV-protective properties of the fabrics. The calculated and measured values of the UV-protective properties of the selected test fabrics were highly correlated, with a correlation coefficient >0.98.

Optical Assessment of Porosity Parameters in Transparent Woven Fabrics

“…The theory of cover factor indicates the part of the area covered by yarns. In general, two cover factors are known [ 22 , 23 ]. One of them is the cover factor related to the one system of yarns only (warp or weft).…”

“…In the case of identical yarns and identical densities of warp and weft yarns (d wa = d we and D wa = D we ), Equation (7) transforms into (8) and (9) [ 23 , 24 ]: …”

Use of Extended Cover Factor Theory in UV Protection of Woven Fabric

“…Due to the insufficient description of the yarn-covered area by the classical existing cover factor theory, the need for an extension of the cover factor theory became apparent. This considers the penetration of UV radiation and/or light through the mesh structure of the fabric as equivalent, although the surface/area coverage of biaxial fabrics (single-layer woven fabrics) with one system of warp and weft yarns consists of surface units covered by only one yarn (warp or weft) and the corresponding number of surface units covered by two yarns (warp and weft) simultaneously ( Figure 1 ) [ 24 ].…”

“…In a previous work [ 11 , 24 ], we evaluated a penetration of UV rays through single layer monofilament PET fabrics trying to find out how much is reflected, absorbed, and transmitted by one yarn and how much from the two yarns in the fabric structure. We calculated quotient as shown in Equations (7)–(9) for every sample.…”

“…Better protection is generally provided by synthetic fibers (e.g., polyester (PET)), due to their molecular structure, while natural ones (e.g., cotton (CO)), except for wool, offer poorer protection [ 2 , 7 ]. The second important parameter is material construction [ 8 , 9 , 10 ], where the high cover factor or closeness of the fabric structure, depending on the type of weave and the diameter of the yarn, prevents the passage of UV rays through the textile. A sufficient level of wearing comfort must be considered [ 4 , 11 ].…”