A New Method for Measuring Water Vapour Transfers Through Fabrics
Résumé
The Skin Model is modified with a frame in order to model the microclimate which is present between the skin and the clothing. The aim of the study is to design and instrument the system by allowing dynamic control of moisture management as a function of time. Resistive humidity sensors are placed at 4 locations in the frame to measure the transfer rate of water molecules through the fabric layer. After checking the reproducibility of measurement, the influence of physical parameters (weight, thickness, moisture regain and fabric design) and thermo-hydric characteristics of fabrics (air permeability, wetting time, one-way transport index, thermal resistance and water vapour permeability) on the transfer rate is analyzed by applying a multiple linear regression. The statistical analysis suggests that one of the main parameters significantly affecting the moisture management is the moisture regain of the fabrics related to its chemical composition, since high fabric moisture regain values lead to low water vapor transfer through the layer. Furthermore, the textile design (1×1 Interlock or jersey), wetting time (WT) and one-way transport index (R) have a low influence on these hydric transfers. To obtain further information, dynamic vapor sorption (DVS) and desiccant inverted cup methods are introduced. For the DVS, the maximum water sorption at 35 °C was determined by the mass difference between 0 and 98 % relative humidity (RH). The desiccant inverted cup method allows moisture transfer to be measured without forcing it unlike frame tests. Methods are compared and this investigation clearly demonstrates that DVS and frame test can be used to assess quantitatively the hygroscopicity, and the moisture transfer rate between the microclimate and the surrounding environment. These parameters are related to the interactive forces between fibers and water molecules, and the ability to store water molecules within fibers by increasing the sample mass.