Acrylonitriel Monomer Grafting on Gray Cotton to Impart High Water Absorbency

摘要

Acrylonitrile (AN) monomer was directly grafted onto gray cotton yarn using a KMnO_4-HNO_3 redox system by a chemical initiation technique. The major factors affecting polymerization of AN, such as KMnO_4, nitric acid, and AN concentration as well as the reaction time and temperature of the polymerization, were studied. The water absorbency of grafted fibers depends strongly on their posttreatment. Saponification of AN-g-cotton with a hot sodium hydroxide solution developed superabsorbency. Absorbency with distilled water and a saline solution (0.9% NaCl) was stdied. Grafting cellulose with AN using a KMnO_4itric acid redox system proceeds by a free-radical mechanism. Use of cotton in the gray form as a starting material rather than a bleached one helps in the better deposition of MnO_2 with subsequent acceleration of the grafting reaction, resulting in better whiteness of the grafted products. The enhancement in the whiteness index could be interpreted in terms of the oxidation of natural coloring matter, which happens to be the objective of the bleaching process. Grafting of AN onto gray cotton results in the eliminationof several preparatory treatments including the conventional bleaching operation, ultimately reducing the water consumption as well as minimizing the unwanted effluent generation. The work has the potential of promoting cost-effective and environmental friendly technologies and techniques.