|Edwards, Judson - Vince
|Allen Jr, Hiram
Submitted to: Textile Research Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2012
Publication Date: 4/24/2012
Citation: Edwards, J.V., Prevost, N.T., Condon, B.D., Batiste, S.L., Reynolds, M.L., Allen Jr, H.C., Ducruet, M., Sawhney, A.P., Parikh, D.V., Slopek, R.P. 2012. Electrokinetic properties of functional layers in absorbent incontinence nonwoven products. Textile Research Journal. 82(10):1001-1013.
Interpretive Summary: Urinary incontinence is common and has an adverse effect on quality of life. It has been previously noted that one-third to one-half of younger and middle age women (40-60 years) and one-half to three-quarters of women >60 years require absorbent incontinence product use protection. However, users of absorbent urinary incontinence products are diverse. An aging population will realize an increased need as do immobilized patients, and although female incontinence represents 80% of the market the male incontinence market is growing with 31 percent of men becoming incontinent by age 85. Since cotton in addition to being environmentally friendly has many other positive attributes that are of value including softness, comfort, non-irritating, hypo-allergenic and breathability, it is our goal to map the usefulness of nonwoven cotton for incontinence control design into absorbent materials by employing fiber surface analysis. The fiber surface properties and layers of nonwoven products are divided into three to four layers including the coverstock, acquisition/distribution layer and absorbent core. These different layers function in the uptake, transport, and storage of urine in the absorbent product. The fiber surface properties that enable these layers to function in cooperation can be analyzed using electrokinetic analysis, moisture content, and absorbance capacity. Thus, this paper correlates the functional properties of known incontinence nonwoven products with their relative charge and polar surface properties so that standards for screening new cotton nonwovens can be performed. This will give an approach to rapidly assessing new cotton blends for the potential use based on fiber surface properties.
Technical Abstract: By applying electrochemical double layer analysis to functional layers of absorbent incontinence products, polar charge gradients between cover stock, acquisition/distribution layer (ADL), and absorbent core were characterized based on zeta potential. Electrokinetic analysis of the cover stock, and ADL of absorbent nonwovens yields surface polarity, swelling, and moisture capacity properties that function within the incontinence material layers preceding the absorbent core where water is stored. Streaming zeta potential, absorbance capacity and moisture content measurements of cover stock and ADL were combined to demonstrate the role of fiber surface polarity, swelling, and water uptake in each product’s mechanism of incontinence control. The aqueous fiber polarity is characterized from pH titration plots that give zeta plateau values for each absorbent layer. The zeta plateau value is useful in assigning the relative hydrophilic/hydrophobic (amphiphilic) character of the cover stock or ADL. The swelling and water uptake capability of the layers is based on the change in zeta potential as the material imbibes moisture and swells to saturation contrasted with the per cent moisture content. Structure/function mechanisms are proposed for urine uptake and transport across the cover stock and ADL for heavy, moderate, light incontinence pads and adult incontinence underwear. The description of functional fluid transport based on the amphiphilic character, swelling and moisture capacity is related to the material’s structural composition and porosity. The mechanism of fluid uptake, wicking and transport from cover stock to ADL is discussed with regard to incontinence volume and urine pH. Using an electrokinetic analysis descriptor for the mechanism of urine transport in absorbent incontinence materials makes possible the expedient distinction of absorbent material design differences based on fiber charge, swelling, fluid transport, and absorption capacity. The application of this approach for screening potential new materials including cotton for improved incontinence control is discussed.