Birefringence, density, and tensile characteristics of oxycelluloses



Investigations have been carried out on the changes in the characteristics such as refractive index, density, single fiber breaking strength, and moisture regain of cotton fibers brought about as a result of oxidation with sodium metaperiodate and potassium dichromate-oxalic acid. The study has also been extended to sodium chlorite-treated and sodium borohydride-reduced oxycelluloses obtained from these oxycellulose products. Results indicate that in case of sodium metaperiodate oxidation, birefringence and density first increase, reach a maximum and then decrease sharply as oxidation is continued, while breaking strength decreases in the initial stages, reaches a minimum, and then increases in the later stages. With dichromate-oxalic acid oxidation, birefringence increases sharply during the initial stages of oxidation and after reaching a maxima, decreases as oxidation progresses, while there is a rapid increase in the values of density during the initial stages followed by a slow rise as oxidation is continued. In case of dichromate-oxalic acid oxycelluloses, breaking strength decreases continuously with the progress of oxidation. Results are interpreted in terms of changes in gross morphology and fine structure of cotton as a result of oxidation and subsequent chlorite and borohydride treatments.