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

Abstract

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.