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The hanging strip water gradient determination and its interpretation on the basis of a capillary bundle model have been applied to a study of the effect of finishing agents on the water-holding capacity of cotton printcloth. Water repellents, cross-linking reactive resins, and surface resins all reduce the water capacity to varying degrees and thereby should make them easier to dry. However, the effect of water repellents is negligible if the fabric is wet out with a surface active agent or by mechanical action, both of which are normally met with in laundering. The reductions in capacity pro duced by reactive or surface resins are not affected by these factors.

The tearing failure of materials depends very strongly on the conditions of use or testing which produce the non-uniform tensile stress which causes such failure. In the trapezoid tear test. the stress pattern is determined largely by variables at the disposition of the operator. The effect of these variables on the tearing strength and the relationship of the latter to the shape of the force-elongation curve have been determined. The tear load is given by an equation of the form where g is the modulus. h is the thickness. L o is the gauge length, α is the trapezoid angle. and E is the elongation of the material at break. The form of the term f ( E ) is determined by the shape of the force-elongation curve and has been calculated for the linear case and for cases yielding convex and concave curves.The validity of this equation has been evaluated with experiments on cotton and rayon fabries in which gauge length, trapezoid angle, thickness and elongation were varied The data are reasonably well tit by the equation using the form of f ( E ) calculated for a linear force-elongation curve. THE mechanical failure of materials is complicated and depends very strongly on the conditions of use or testing under which it occurs. This is particularly true of tearing failure. The characteristic feature of the tearing process is that it is ;i response to a non uniform tensile stress. If the stress pattern ran he denned, it is then possible in principle to relate the behavior of the material to its performance under a uniform stress, as in the usual tensile test.The stress pattern around a tear in a test sample is determined first of all by the geometry of the testing arrangement. In some cases, such as the tongue tear test used in textile testing, the stress application ;it the actual tear locus may also he determined largely lvy the preliminary response of the fabric through yarn slippage, trellis distortion 17 J. or the like. In other tests, these factors are less important and the stress pattern is controlled to a greater degree by variables at the disposition of the operator. The trapezoid tear test is of the latter sort and lends itself to analysis if the reactions normal to the straining direction are neglected. Tlte origin of the trapezoid tear test appears to he rather obscure The references cited hy ~{il1ard r 31 ] indicate that a test of this type was in use alout thr time of Wortd War I among workers studying the properties of aircraft fabrics. The acute angle of the trapezoid then used was larger than the angle in the· present standard tc>~t ( 1 ~ . The only theoretical study of the test seems to ht, that of llager, Gagliardi, and NValker r 21. whose analysis resulted in an equation relating tear strength to t'xtensibility and breaking strength The treatment of the trapezoid tear test giivrn in this paper is somewhat more detailed than that given by 1 i ager, Gagliardi, and Walker and leads to some new relations between the geometry of the test and the tear strength. In particular, the anKle:> of the trapezo...

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Much available chemical evidence supports the hypothesis that covalent cross-linking is the best way to improve the resilience of cellulosic fabrics. This paper reviews the theories relating physical properties to cross-linking in rubbery polymers and shows that they apply in some qualitative aspects to cellulose. Particularly, the observed changes in swelling, solubility, modulus, tensile strength, and resilience are consistent with these theories.On the basis of published data, the concentration of intermolecular cross links is estimated ; it is found that at least every twenty-fifth accessible anhydroglucose unit has to be intermolecularly cross-linked when maximum crease recovery values are attained. In rubbery polymers, substantial changes in mechanical properties are obtained at much lower levels of cross-linking. This difference between cellulose and rubbers in response to cross-linking is probably due to the polar nature of cellulose.IT IS widely accepted that cross-linking is the most efficient method to impart high resilience, good crease recovery, and dimensional stability to cellulose fabrics. The cross-linking hypothesis was first advanced by Meunier and Guyot [29] J in 1929 for the formaldehyde-cellulose reaction. It obtained wider attention in 1948 through the work of Cameron and Morton [5], who based their conclusions on the lowered moisture regain, water imbibition, and solubility of rayon samples reacted either with urea-formaldehyde or melamine-formaldehyde precondensates or with formaldehyde or glyoxal alone. It had, however, been known [2, 8, 511 and has reently been confirmed by Reeves et al. [ 36] that wet state treatments of cellulose with formaldehyde . increase the moisture regain and water imbibition. Furthermore, reduction in the solubility of cellulose may also be caused by simple single-ended substituton on the cellulosic hydroxyls. The evidence provided by Cameron and Moron was therefore not unequivocal. , A very powerful argument in favor of the crosslinking hypothesis is the general experience that only difunctional reactants are particularly efficient in improving the resilience of cellulosic fabrics. For example, Steele and Giddings [42,43] found that monomethylol urea increased the crease recovery of cotton to a much lesser extent than dimethylol urea. Most known cellulose cross-linkers are able to polymerize when reacted in the absence of cellulose. It has been argued that these compounds improve resilience by forming polymers within the fiber (25J ] and thus stabilizing the physical entanglements of the molecules ( 28 J . One could imagine that complicated cross-linked structures are obtained by polymerizing difunctional reactants and that the resulting three-dimensional networks are more efhcient in stabilizing the fabric than the linear polymers derived from monofunctional reactants. However, this argument is weakened by the available data indicating that certain reactants do form covalent links with cellulose. This has been shown by Wagner and Pacsu [49] by methylation of...

The chemical changes in cellulose fiber which lead to various wet: dry crease re- , covery ratios are reviewed. Covalent cross-linking of a dry fiber enhances both wet and dry recovery, and the ratio of the two values is believed to depend on the relative accessibilities of the fiber to water and to the cross-linking reagent. Water-sensitive links between cellulose chains can give high dry and low wet crease recovery. Cross- linking reactions carried out when the fiber is wet and swollen lead to a higher degree of intrachain reaction, which is equivalent to substitution, and to some interchain cross links. The swelling of such a fiber in water leads to good wet crease recovery, although the dry recovery is not improved. To achieve good tumble-dry wash-wear behavior, both wet and dry crease recovery must be increased In line- and drip-drying, the we crease recovery has more sig nificance than the dry.

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THE INFRARED absorption spectrum of methyl cellulose has not been reported in the literature. A technique for drying and mounting thin films so that their spectra can be obtained in the dry state is described herein, and the spectra of methyl cellulose, cellulose, and starch are presented.The films were made by allowing a solution of the material to evaporate on a clean mercury surface.