Studies on the capillary wetting kinetics of fiber assemblies by the electronics techniques

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A new apparatus has been designed which gives an accurate measurement of the rate and height of capillary rise of water in a porous material, such as fabrics, from the initial moment of contact with water.When two parallel plate electrodes are immersed in water, the increase of capacitance across the twin electrodes is directly proportional the height of water between the electrodes. The circuit was used to detect the level of water contained in a vertical strip of fabric put between twin parallel plate electrodes and to give a good linear relation btween capacitance and water level. One of twin electrodes is a thin stainless steel plate and the other tinned wire coil mounted on glass plate, which are coated with Teflon film to keep a good insulation.The progress of liquid rise in a fabric, thus the increase of capacitance is recorded automatically from the first moment of contact with the liqid. Such a water level-capacitance conversion method has a very quick response, and so we can obtain a real time record of the movement of water. An attempt has been made to analayze the rate of capillary phenomena by using Washburn equation,from the accurate results obtained.