J. David Reid

Preparation of Soluble Yarns by the Carboxymethylation of Cotton

Water- and alkali-soluble cotton fibers, yarns, and threads have been prepared by two methods. The cotton is preferably pretreated by pressure-kiering in 2% sodium hydroxide to remove the noncellulosic materials, and then treated with monochloroacetic acid and sodium hydroxide by either a one-step or a two-step process. Where only disintegration or partial solubility is required, the one-step method is sufficient. Where complete solubility of the cot ton is required, the process must be carried out in two steps: a mild, followed by a stronger treatment. The treated cotton is neutralized in alcohol with acetic acid to produce water soluble products or with strong acids in alcohol to produce water-insoluble but alkali-soluble products. Cotton in the form of sliver, yarn, and thread has been successfully treated.

Effects of Cross-Linkage in Wrinkle-Resistant Cotton Fabrics

The cross-linking of cellulose in cotton fabric with three wrinkle-resistance finishing agents has been investigated. The three agents used were dimethylol urea, dimethylol ethyleneurea, and formaldehyde. With all three compounds, maximum crease recovery angles are obtained with a substitution of 0.04-0.05 cross links per anhydroglucose unit. As crease recovery angles increase, the elongation and permanent set caused by an 8-kg. tensile load on a 1-in. fabric strip decreases. Permanent set approaches zero near 135° warp crease recovery. Changes in the load-elongation curves indicate elastic modulus increases as crease recovery angles increase. Treatment of fabric to the same crease recovery angles with the three compounds reduces tearing and breaking strengths to different extents. The differences are due to different amounts of cellulose degradation caused by the aciclic catalyst systems and not to the structure of the cross links.

Studies on the Partial Carboxymethylation of Cotton

Additional studies have been made on partial carboxymethylation—the reaction between mono chloroacetic acid and cotton in the presence of sodium hydroxide—and on the products ob tained. A thorough investigation of the time and temperature of reaction and concentration of reagents showed that relatively small amounts of monochloroacetic acid, properly applied, alter the properties of cotton considerably. Pilot-scale carboxymethylation of cloth was conducted which showed that it is possible to use standard textile machinery in the process. The cloth resulting from this treatment had a crisp liand with a slightly starched feel. More detailed investigations than reported previously were made, and it was found that the tensile strength and elongation of treated cotton are increased, dyeing properties are changed, and soiling-resistance and soil removal are increased. It was also learned that the treated materials are unaffected after one years storage.

The Preparation of Partially Cyanoethylated Cotton with Acrylonitrile

The preparation of partially cyanoethylated cotton with acrylonitrile in the presence of sodium hydroxide is described, including effects of changes in time, temperature, and concentration of reagents. Products with retention of the fibrous form have been ob tained with degrees of substitution up to 2.7 cyanoethyl groups per anhydroglucose unit. Hydrolysis of the cyanoethyl group occurs readily under alkaline conditions and re sults in both cleavage and conversion to the carboxyethyl group. Maximum conversion in the latter case was 29%.

The Nonaqueous Carboxymethylation of Cotton

Cotton fiber, thread, and fabric were carboxymethylated by a nonaqueous process. Activated cotton was impregnated with an isopropanol solution of monochloroacetic acid and refluxed with 0.3% sodium hydroxide in a mixture of methanol and isopropanol. Degrees of substitution ranging up to 0.09 were achieved. Higher values can be ob tained by retreatment or premercerization. Four varieties of cotton fiber have been carboxymethylated by this method. Cor relation between the reactivity and the original physical properties of the fibers has been shown. Textile properties of fabric treated by this nonaqueous method and those of a sample treated by the usual aqueous alkali method were compared at equal substitution. The α-methyl-, α-ethyl-, α-propyl-, α-decyl-, and α-cetylcarboxymethyl derivatives of cotton were prepared in low degrees of substitution, using the appropriate α-halo carboxylic acid as etherifying agent in the nonaqueous reaction.

The Partial Carboxymethylation of Cotton to Obtain Swellable Fibers, I:

For the purpose of obtaining quickly swellable fibers to aid in making cloth less pervious to water, cotton fibers have been partially carboxymethylated. Different degrees of swelling have been obtained and the properties of the resulting products are described.

A Progress Report on Cyanoethylated Cotton

The mechanism of cyanoethylation of cotton is discussed, and it is shown that for best effi ciency the pick-up of sodium hydroxide must not exceed 15% of the weight of the cotton. Measurements of physical properties show that any increases in the breaking strength or elon gation of yarns are results of changes in frictional forces. The physical properties of cyano ethylated fabrics reflect the properties of the yarn and are also dependent on fabric construction. Extremely high resistance to flat abrasion is obtained with high cyanoethyl substitution. The density of cyanoethylated cotton is shown to be linearly related to the nitrogen content, and the spread of values obtained has been found to give an estimate of the uniformity of treatment. Cyanoethylated cotton can be dyed by methods developed for polyacrylonitrile fibers such as those employing acid dyes in the presence of cuprous ion, and the dyed samples so produced are suitable for cross sectioning for microscopic examination. The intensity of dye color can be used as a measure of the amount of cyanoethylation.

Imparting Water-Repellency to Textiles by Chemical Methods A Review of the Literature

The literature relating to the water-repellency of textile materials has been surveyed for those articles and patents dealing with the production of this property by chemical methods. The 332 pertinent references found have been abstracted and classified on the basis of the type of compound used to impart water-repellency. No attempt has been made at critical evaluation. Reactions, where known, have been described with the aid of equations. Additional references for collateral reading are given. An index which has been compiled of the chemical water-repellent agents proposed is being published by the U. S. Department of Agriculture as Research Publication AIC—179.

Flame-Resistant Cotton Fabrics: An Emulsion Treatment Using an Organic Phosphorus- Bromine Polymer

Flame-resistant cotton fabrics have been prepared by treatment of the fabric with an aqueous emulsion of an organic polymer, prepared from bromoform and triallyl phosphate. The finish is durable to repeated laundering, and when applied with proper plasticization to fabrics of 8-9-oz weight does not materially change other textile properties. The treatment may be applied on conventional textile finishing equipment.

Phosphorylated Cotton Cellulose as a Cation-Exchange Material:

It was found that phosphorylated cotton cellulose made by the phosphoric acid-urea method has a high cation-exchange capacity and when used in the form of a coarse fabric it shows good now characteristics in the calcium-hydrogen cycle. Its cation-exchange capacity increases with increasing phosphorus content and at a phosphorus content of about 5 percent the cation- exchange capacity reaches about 1,000 milliequivalents per kilogram. It is possible that specialized uses may be found for phosphorylated cotton cellulose, especially in the fabric form.