Electrical Resistivity of Conductive Leather and Influence of Air Temperature and Humidity

Abstract

Leather is a material that has been used in different applications for centuries. Today, living in the era of high-tech¬nology, we are surrounded by smart products. For this reason, traditional products must be changed or im¬proved in order to support and make us more comfortable while using them. For instance, the touch screen display in electronics products is a smart phone’s or a tablet computer’s primary input device. Still, traditional leather will not function properly in a cold climate or other specific conditions. To make it conductive in such conditions, the double in-situ polymerization of the pyrrole coating method was used. The aim of this study was to observe the electrical properties of conductive leather. At the same time, it stands up to a wide range of different air temperatures, and relative and absolute humidity. These properties are essential because de¬signers and textile engineers should be familiar with them when they decide to use materials in different smart products. Electricity conductivity tests were carried out in year-round temperatures from 7.5 °C to 28.1 °C, with a relative humidity from 18% to 77% and a vapor air concentration from 2.77 g/kg to 12.46 g/kg. The so-called “multiple-step method” was used to test leather’s electrical resistivity for the first time. The method considers a material’s compressional properties and provides an indicator inherent for a material’s electrical properties, regardless of the mass and shape of samples. The results showed a strong dependence between water vapor air concentration and electrical resistivity, described using the formula ρ = 1.3103 H−1.04 Ωm, with a correlation coefficient of 0.87. There was no relation between relative humidity and electrical resistivity, and resistivity and air temperature. Also, the results confirmed again that changes in the shape of the sample used during tests did not influence the measurement’s results, but supported the appropriateness of the measuring method.

Influence of Humidity on the Electric Resistivity of Leather: Mathematical Modelling

“…On the other hand, Figure 1b shows a good relationship with absolute humidity. In a previously published paper, these data were fitted to H -1.042 or H -1.059 , depending on whether sheets were included or only strips were taken into account [17]. The measuring technique was especially designed for textile samples and has been described extensively in literature [15][16].…”

“…Therefore, in order to make resistive traditional leather conductive, different groups have worked with different methods [2][3][4][12][13][14]. In previous contributions, sheep crust leather was coated with polypyrrole using the double in-situ polymerization method and the electrical resistivity of conductive leather using the "multiple-step method" [15][16] in different air temperature and humidity conditions was measured [17]. In this paper, a theoretical analysis of the influence of humidity on the electric resistivity of leather was performed.…”

A Review of Electro Conductive Textiles Utilizing the Dip-Coating Technique: Their Functionality, Durability and Sustainability

“…The electrical conductivity of functionalized flat fabrics (woven or knitted) depends on numerous factors such as the fabric’s structure (density, roughness, volume fraction of pores) [ 78 , 79 ], the uniformity of applied compounds (type and concentration) [ 41 , 77 ], the number of dipping and intermediate drying [ 77 ], the measuring method/protocol (measuring line/distance) and the environmental conditions (air humidity and temperature) [ 70 , 80 ]. Tokarska [ 79 ] studied the electrical resistivity of circle-shaped woven and square-shaped knitted fabrics in dependence on textiles’ surface roughness.…”

“…Afterwards, the sheet resistance decreased slower as it reached the saturation point. Kazani et al [ 80 ] reported great dependence between water vapor air concentration and electrical resistivity, and, on the other hand, no relation between relative humidity and electrical resistivity, or resistivity and air temperature.…”

“…Figure 5 shows a scheme of different measuring systems as described in [ 78 ]. Kazani et al [ 80 ] used the so-called “multiple-step method”, which considers the compressional properties of a material, regardless of the mass and shape of samples, providing an indicator inherent for a material’s electrical properties.…”