Characterization of liquid transport in needle-punched nonwovens. I. Wicking under infinite liquid reservoir

Abstract

The study of wicking characteristics of fibrous materials has received significant attention from both academic and industry over many decades. Wicking describes the liquid transport behavior of fibrous assemblies, and plays a critical role in the processing and end use of nonwovens in many application areas including medical, geotextiles, filtration, etc. However, the analysis of wicking in a nonwoven materials is complex because of random arrangement of capillary tubes formed by fibers, and therefore, we must have to rely on the experimental techniques to appraise their wicking performance. In the present work, the wicking characteristics (rate and amount of liquid rise) of different nonwovens (made from polypropylene fibers) under an unlimited or infinite liquid reservoir system has been analyzed using a newly developed computerized wicking apparatus based on capacitance principle. Some factors, i.e., fiber denier, mass per unit area and needling density, were chosen for the experimental plan to find their significance on the vertical wicking. It has been found that the rate and extent of wicking is significantly affected by changing the levels of above factors (p<0.05). The rate and amount of liquid rise was increasing with increase in needling density and mass per unit area of nonwoven samples. Samples made from higher fiber denier (15 denier) were showing poor wicking results compared to lower denier samples (2.5 and 6 denier). Further work is still needed to examine other factors on the wicking to further improve our understanding of liquid transport in such highly complex porous networks.