Neutron activation analysis as a method for measuring soil removal of unsaturated oils and for estimating their degree of aging on fabric

Abstract

Neutron activation analysis of bromine-tagged oils on fabric provides a quantitative method for evaluating the degree of aging of unsaturated oils on fabric as well as a new method for measuring their soil removal by estimating the quantity of double bonds, before and after laundering. When aged at 21°C for 5 wk, 62, 63, and 20% of double bonds remained for oleic acid, triolein, and squalene, respectively. At 40°C, no double bonds were left after aging of oleic acid and triolein, whereas about 8% of the double bonds remained for squalene. A comparison of this method with the radiotracer method for soil removal measurements shows good agreement between the two methods. Proper treatment time for bromine tagging of unsaturated oils on fabric is any time between 90 s and 10 min under the bromination procedure used. The tagging of double bonds by bromine vapor has advantages of the exact one-toone reaction ratio between Br 2 and the number of double bonds of unsaturated oleic acid or triolein, as well as a much lower cost than other tagging reagents like OsO 4 . Because blank unsoiled fabric was shown to take up Br 2 , fabric swatches of the same size should be used as controls in neutron activation analysis. This method has advantages of its sensitivity to small amounts, use of nonlabeled soil, quantitative measurement, and ease of sample preparation over the chemical measurement of iodine value. JSD 1, 227-233 (1998).Although various methods for measuring and evaluating detergency have been developed, the type of soil and soiling level being used during an investigation can limit their applications. The gravimetric method (1,2) is only useful for heavily soiled fabric. Reflectance methods have been used for carbon, clay, colored stains, and oily soil on colored fabrics; however, these reflectance readings are not a quantitative measurement of the amount of soil present on the fabric (1-3). Radiotracer analysis of residual labeled soils left on fabric after washing provides the absolute soil content remaining on the fabric swatch and also can be applied to any soiling level (1,2,4). It is, however, only applicable to laboratory experimentation with radiolabeled soils.Neutron activation analysis (NAA) is a recognized analytical method for determining the amount of clay soil removed from fabric during a wash cycle (1,2,5). Netzel et al.(6) first reported this method for determining the amount of kaolinite clay soil present on cotton cloth before and after washing by gamma scintillation counting of the 28 Al.NAA has been applied in other aspects of the textile field, for example to measure elements present on fibers or fabrics qualitatively or quantitatively. Guion and McGregor (7) measured the amount of Cl atoms taken up by acrylic fabrics after exposure to a salt solution. The amount of bromobenzene was measured to determine whether a bromine-containing dye carrier had been washed from the surface of poly(ethylene terephthalate) (PET) fibers (8). Chemical tagging of functional groups using Cs and Br followed by neutro...

Evaluation of Detergency Using Artificially Soiled Multifiber Fabrics

“…For the purpose, the exact evaluation of detergency is necessary and hence well-defi ned model systems have been proposed to clarify the detergency mechanism [12][13][14][15][16][17][18][19] . However, conventional evaluating methods with artifi cially soiled fabrics are needed because the fabric has complicated geometrical structure [20][21][22][23][24][25][26][27][28] .…”