Howard J. White

Mechanical Properties of Textiles, I:

In this paper the spring-dashpot theory which has been applied in previous papers in this series to single fibers and to yarns is applied here to the experimental investi gations of a plush fabric which have been published by Fox and Schwarz. This serves to outline the experimental methods which should be followed if the data are to have maximum theoretical significance.

The absorption of cationic surfactants by cellulosic materials: I. The uptake of cation and anion by a variety of substrates

Abstract The interaction between cationic surfactants and cellulosic fibers has been studied. Most of the work involves cetyltrimethylammonium bromide (CTAB) and four substrates: kiered cotton, a medium-high-tenacity viscose rayon, a viscose rayon monofil, and oxycellulose. Absorption isotherms for the cation and anion of the surfactant were measured and some attention was given to rates of absorption and to the effects of temperature, added electrolyte, and solubilized dyes. Two major absorption processes occur in the concentration range studied: cation exchange and ion-pair absorption. The cation exchange is dependent on the exchange capacity of the substrate. The ion-pair absorption begins to become important in the vicinity of the critical micelle concentration of the surfactant and also seems to depend on the cation-exchange capacity of the substrate. If the ion-pair absorption is assumed to consist of a clustering of ions on exchanged long-chain cations, the results for all but very high ionic strengths can be explained. In the presence of large amounts of added electrolyte an additional ion-pair absorption seems to occur.

textile research journal The Adsorption of Water by Swelling High Polyrneric Materials

This paper contains a discussion of the water-adsorption properties of a class of long-chain materials with many polar groups, which includes most textile fibers. The process discussed is distinguished from the adsorption by substances such as metal and metallic oxide catalysts in that it is not strictly a surface phenomenon, the adsorbent swelling as water is adsorbed. It differs from simple hydrate formation in that the water uptake is a continuous function of relative humidity, although in theory this behavior can be considered to be caused by the existence of an infinitely large number of possible hydrates. And, finally, it is distinguished from adsorption by liquids by the fact that the adsorbent possesses, and retains during the adsorption process, a certain amount of dimensional stability. In the first part of the paper a summary is given of some experimental data. This summary is not a complete review of previous work but is rather an outline of the data on the various phe nomena associated with the adsorption process. The purpose of this section is to give as much information on the fundamental adsorption process as possible rather than to give data for a large number of representative substances. For this reason many references, especially to chemically modified fibers (which contrast individual members of this class but do not contribute new infor mation on the fundamental adsorption process), are omitted. In the second section a review of previous theoretical treatments is given and a new theory of the adsorption isotherm for this class of substances is proposed. This treatment is derived by the methods of statistical mechanics and expresses the adsorption isotherm in terms of the relative humidity, regain, and molecular parameters in the simplest case. The application of the theory to experimental data shows surprisingly good agreement between theoretical and experimental isotherms, considering the approximations involved. In some cases missing data are estimated from known data for similar substances. The third section contains a discussion of adsorption hysteresis in terms of the theory developed here and the theory of absolute reaction rates, as well as a discussion of the constants of the isotherm.

The absorption of cationic surfactants by cellulosic materials: III. A theoretical model for the absorption process and a discussion of maxima in absorption isotherms for surfactants

Abstract A theoretical model is proposed to account for the results observed when cationic surfactants are absorbed by cellulosic substrates. The model consists of the absorption of cations by an exchange process followed by a clustering of ion pairs on the exchanged cations. When this model is combined with a mass-action treatment of the surfactant solution, absorption isotherms, similar to those found experimentally, are obtained. In particular, there are maxima in the absorption isotherms. A discussion of the factors which lead to maxima is given, and a model to account for the maxima observed with anionic surfactants is proposed.

The Swelling of Human Hair in Water and Water Vapor

Data are presented on the swelling of free and strained hair fibers in water and water vapor. The strained hair fibers were either under constant load or at constant elongation. In some cases rates of swelling are also shown. The swelling isotherms of the free fibers follow the volume changes predicted from density measurements (for wool) except at very high relative humidities. Straining the fiber may either increase or decrease the amount of swelling, depend ing on the type of experiment. An attempt to develop a statistical mechanical model to explain the equilibrium absorption and swelling behavior of a hair fiber is only partly successful. Finally, there seems to be evidence from the rates of swelling to indicate inhomogeneities in the hair with respect to its response to mechanical deformations.

The Swelling of Hair and a Viscose Rayon Monofil in Aqueous Solutions

Equipment for measuring the swelling of nearly round single fibers in a variety of solutions is described and has been used to make measurements on the swelling of human hair and a viscose rayon monofil. In particular, measurements have been made on the swelling of both types of fiber in various alkali halide solutions and of the hair in HCI solutions. Except for NaCl solutions, the solutions used in this work caused swelling beyond that caused by liquid water, indicating that the solutes were absorbed by the fibers. The results using LiCl and LiBr solutions are noteworthy in that considerably more swelling occurs in these solutions than in water. The increase in swelling over the water-swollen value is about 25% in the case of hair and 60% in the case of rayon. The high degrees of swelling of hair must be reached by successive replacement with increasingly concentrated solutions, direct immersion of a water-swollen hair into a concentrated solution causing deswelling. For the viscose rayon, either method causes similar swelling. The swelling changes in hair caused by altering the different variables common in an acid dye bath for wool have also been studied.

An Experimental and Theoretical Study of the Adsorption and Swelling Isotherms of Human Hair in Water Vapor

Quantitative data on the length and diameter changes accompanying the adsorption of water by human hair are given as functions of the relative humidity. Data are also given on the effects of a load on the swelling isotherms. A theoretical treatment is proposed which accounts in a semi-quantitative way for the swelling isotherms and the effects of tension as well as for the adsorption isotherm.

The Interaction of Hair Fibers with Alkali Bromide Solutions

The interaction of hair with alkali bromide solutions has been studied by measuring the amount of salt taken up from a given solution, using a radioactive-tracer technique, and the amount of water taken up from the solution, using a gravimetric technique. It has been found that: (1) alkali bromides are taken up in a manner primarily dependent on the activity of the salt in the solution; (2) the amount of water absorbed is increased over the normal regain by the presence of the salt in the hair; (3) the ratio of salt to water is greater in the hair than in the external solution; (4) the rate of absorption of the salt is slower than the rate of diffusion of the same salt in water; (5) both rates and equilibrium are temperature- sensitive. The interpretation of these results in terms of various simple models of the absorption process is discussed.

Some Theoretical Considerations of the Dyeing of Cellulose Acetate with Disperse Dyes

Theoretical aspects of the disperse dyeing of secondary cellulose acetate are considered. Two models for the dyeing process are develpoed provisionally, one based on mixing of polymer segments with absorbed molecules, one based on absorption onto sites within the fiber. From a consideration of the experimental results available, the model based on mixing is rejected as unsatisfactury. The model based on absorption onto sites is quatitativety consistent with most of the experimental results available. Although both models are crude approximations, the qualitative agreement with experiment shown by the site model offers the possibility that it may be used as a stepping stone to further experiments and development of a more exact theory of disperse dyeing for cellulose acetate.

The absorption of cationic surfactants by cellulosic materials: II. The effects of esterification of the carboxyl groups in the cellulosic substrates

Abstract Viscose rayon and oxycellulose containing a high concentration of carboxyl groups have been esterified at the carboxyl group using ethylene oxide. This reagent was chosen to minimize changes in accessibility caused by the esterification reaction. Measurements were made of the carboxyl contents, of the capacities of the samples to absorb water, and of their capacities to absorb the cation and anion from solutions of cetyltrimethylammonium bromide. These last measurements were made to test the hypothesis advanced by Sexsmith and White (1) that absorption of ion pairs from the surfactant solution was a clustering process dependent on the presence of exchanged cations which served as nuclei. The marked decrease in ion-pair absorption found after esterification was in agreement with this hypothesis. Some other properties of the esterified oxycellulose samples are also discussed.