Influence of Relative Humidity on Electrical Properties of Textile Laminates

The aim of this paper is to determine the influence of relative humidity on the comfort and electrical resistance properties of textile laminates in order to predict possible changes in footwear protection levels. Four textile laminates of different structure and fibre nature were selected for the study. It was determined that water vapour absorption of textile laminates strongly depends on the humidity of the storage environment. The absorption ability of laminates increases about 1.8 – 3 times as relative humidity increases from 65 % up to 95 %. The degree of increase depends on the textile laminate structure and the nature of the materials layers. The electrical properties of protective footwear can be influenced by the structure, thickness, relative humidity, and voltage of textile laminates. For textile laminates composed of natural and synthetic fibres and polymer foam as insulators, the resistivity increases with the thickness of the synthetic fibre and polymer layer. At low voltage (U = 100 V), the textile laminates tested became insulating materials, as the electrical resistivity exceeded the threshold values for antistatic materials in all relative humidity ranges. At high voltage  (U = 500 V) the electrical resistivity of textile the laminates drops dramatically when the relative air humidity increases and the level of protection of the laminates depend on the amount of moisture absorbed and the nature of the layer materials. The laminates possessed insulating properties in environments of up to 65 % relative humidity. In a high humidity of the environment, the insulating properties of textile laminates turned to antistatic, except for laminate without a polymeric membrane, which became conductive.