Modification of the physical and chemical structure of cotton and effect on sorption and coloration properties

• Main Author: Kljun, Alenka
• Published: University of Leeds 2013
• Subjects: 677.21
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595846

Cotton fibres develop over four stages: initiation, elongation, secondary-wall thickening, and maturation. They develop a significant crystalline structure during the elongation stage of its development. Dyeing these fibres was used as a new method to see cellulose development. From all measured properties it was concluded that the most significant changes in crystallinity of developing cotton fibres occur between 17 and 24 days after flowering. When native cellulose (Celluose I) is treated with certain alkali concentrations. cellulose II is formed. The aim of this research is to observe and assign qualitative crystallinity changes in cotton fibres using X-ray diffraction and ATR FT-IR spectroscopy subsequent to sodium hydroxide treatment and to compare these observations with immunoassay labelling techniques; such biological techniques have never been used to quantify molecular changes in polymers. It was demonstrated that the use of molecular probes attached to carbohydrate binding modules (CBMs) provided molecular recognition for cellulose with differences in crystallinity, and enabled visual representation of the presence of crystalline and amorphous cellulose. Cellulose and chitin are the most abundant polysaccharides found in nature. Cotton is modified using genetic or chemic methods to incorporate chitin or chitosan residues into the fibre. Objective of this work is to create a reproducible technique to test genetically modified cotton fibres to see if there are any detectable differences between control and modified fibres. Sorption of dyes was studied to understand the mechanism of adsorption for dyes on cotton. Genetically and chemically modified cotton fibres were typical of a Freundlich isotherm at both pH4 and pH7. Obtained data from the study of the effect of temperature on sorption isotherms showed the highest overall exhaustion (qe) at lower temperatures (20-40°C), probably due to the exothermic process.