S. N. Pandey

A Study of the Effect of Anhydrous Liquid Ammonia Treatment on Cotton1

A study of cotton treated with anhydrous liquid ammonia at different temperatures is reported. Effects of treat ment on physical and mechanical properties, chain length, moisture regain, and cellulose accessibility have been studied. The treatment brings about considerable changes in some of the above properties and also in fine structural properties of cotton as revealed by infrared and electron microscopic studies.

Studies of Chemically Modified Cotton Part I: Effect of Chemical Treatments for Varying Periods on Crystallinity and Certain other Properties of Cotton1

High crystallinity of cellulose is the cause of undue stiffness and brittleness as well as low absorptioh and chemical reactivity. With a view to overcome these drawbacks and bring about changes in the elastic and other properties of cotton fibers, two cottons, Gaorani and 170-Co.2, were treated with anhydrous ethylamine, diethylamine, pyridine, and aqueous solutions of sodium hydroxide (30%) and potassium hydroxide (40%) for 15 min to 50 hr. Modified lint samples showed interesting changes in cellulose crystallinity and moisture regain, on treatment with ethylamine, sodium hydroxide, and potassium hydroxide after certain periods. Some of the treatments also showed a marked effect on the degree of polymerization and the tensile, mechanical, swelling, and optical properties of the fiber. Moisture regain and degree of swelling were found to be higher in the case of samples treated with alkali, compared with those treated with amines.

Effect of Phosphoric Acid Treatment on Physical and Chemical Properties of Cotton Fiber1

Recent work on inter- and intra-crystalline swelling in phosphoric acid has been reviewed. I)etailed chemical treat ments on MCU-3 cotton fibers under different conditions of reaction with phosphoric acid have been reported. Changes in fiber characteristics after swelling have been studied with respect to moisture regain, accessibility by sorption ratio, iodine absorption methods, and degree of polymerization (DP). Effect of treatment on fiber strength, elongation, and other mechanical properties have also been discussed. It is observed that inter- and intra-crystalline swelling of cotton fiber with phosphoric acid depends on temperature, concentration, and various other factors. Treated samples showed appreciable change in moisture regain, accessibility, and DP values with the treatment concentrations above 77% at different temperatures. The changes were more marked when swelling was carried out at 10°C than at a higher tem perature. Relationships between these properties are also discussed and accessibility by iodine absorption, DP, strength, elongation, toughness, and stiffness with the accessibility by moisture sorption ratio have been co-related.

Intercrystalline and Fine Structural Properties of Chemically Modified Cottons by Infrared Spectroscopy

indicated the presence of cross links by obtaining a stitfer load-extension curve in formic acid. Asquith and Parkinson [1, 2] have shown that both of these treatments insolubilize a-keratose, indicating reaction with the microfibrillar component. The fact that the former treatment is able to thermally stabilize the a-helices suggests a more intimate association of the new cross links with the helical component, which is not achieved by the latter treatment. However, it is possible that degrada-

Improved Durable-Press Cotton by a Two-Step Poly-Set Process Part II: Crosslinking of Cotton Cellulose with Dimethyloldihydroxyethylene Urea

A crossrinking treatment on scoured, bleached, mercerized, and desized cotton fabric with dimethyloldihydroxyethylene urea (DMDHEU) by a two-step poly-set process is reported. The fabric was also treated with DMDHEU by the conventional pad-dry-cure tecnhique. The resin-finished fabric, along with a control, were studied for various physiochemical properties by standard methods. The number of crosslinks (expressed as CL/GPU) and length of crosslinks were calculated from formaldehyde yields and nitrogen values. The data on resin add-on, CL/GPU, and length of crosslinks of cotton crosslinked with varying concentrations of the resin in the presence of polymerization catalysts is discussed. The add-on values in the case of the sample treated by zinc acetate was much higher compared to the similar sample treated in the presence of magnesium acetate. The number of CL/GPU and length of crosslink increased with the increase of resin concentration. Homopolymerization of resin was evident in step 1. The fabric processed in step 2 showed marked improvement in wrinkle-recovery angle and other properties such as strength, elongation, abrasion, and toughness, compared to the samples treated by the conventional process. The relationship between various properties of the fabric is also dealt with.

Derivative Infrared Spectra of Ramie

A derivative technique has been applied to infrared absorption spectrophotometry of ramie in the regions 4000-2500 and 2000-700 cm-1. The second derivative spectra at different scan speeds and differentiator time constants in these regions have been compared with the absorption (zeroth derivative) spectra. The derivative spectra mea sure the slope or curvature of the absorption contours, facilitate to resolve, and detect absorptions that are unresolvable due either to band overlap or low intensity. This method may thus provide more detailed information on the fine structure of cellulose.

Studies on Chemically Modified Cotton: Part II: Effect of Different Concentrations of Chemicals on Crystallinity and Certain other Properties of Cotton

This study describes the effects of chemical treatments with varying concentrations of ethylamine, ethylenediamine (EDA), potassium hydroxide (KOH), and lithium hydroxide (LiOH) on various properties of cotton fiber, such as crystallinity, moisture regain, DP, and tensile, mechanical, and optical properties. Concentrations of 70–90% EDA, 70% and higher ethylamine, 20% and higher KOH, and 7–10% LiOH showed marked changes in cellulose crystallinity and some other properties. Maximum change was produced by KOH and ethylamine, while EDA produced the least effect. Most of the treatments also reduced the DP, tensile strength at 0 gauge and birefringence values, but increased moisture regain, percent elongation and fiber toughness considerably.

Studies on Chemically Modified Cotton: Part IV: Studies on the Relationship between the Properties of Untreated and Chemically Modified Cotton Fiber

2. Pandey, S. N. and Iyengar, R. L. N., Studies on Chemically Modified Cotton. Part I: Effect of Chemical Treatments for Varying Periods on Crystallinity and Certain Other Properties of Cotton, Textile Res. J. 39,15-23 (1969). 3. Pandey, S. N. and Iyengar, R. L. N., Studies on Chemically Modified Cotton. Part II: Effect of Different Concentrations of Chemicals on Crystallinity and Certain Other Properties of cotton. Textile Res. J. 39, 24-31 (1969).

Studies on Chemically Modified Cotton Part III: Chemical Treatments at Different Temperatures and Their Effect on Crystallinity and Various other Properties

Purified lint samples of 170-Co.2 cotton were treated with different molar solutions of LiOH and KOH at 20, 30, 40, and 55°C. Treated and untreated products were examined for various properties such as moisture regain, cellulose crystallinity, viscosity, tensile, mechanical, and optical properties in order to determine the effect of treatment temperature on these properties. Treatments with both chemicals produced marked changes in the properties depending upon the molarity of the solution. However, the changes were similar at different temperatures. Moisture regain was found to increase and crystallinity to decrease with decrease of temperature; relative viscosity, bundle strength at 0 gauge length, elongation, and toughness were found to be slightly higher at 20°C than at higher temperatures; n11 and birefringence were slightly higher for 30° than for 40°C.