Photo-oxidation of rice starch. Part I: Using hydrogen peroxide

A process of oxidation of rice starch using UV irradiation and hydrogen peroxide (H2O2) as a photo-initiator was adopted. Factors affecting the photo-oxidation process were studied. The extent of oxidation was determined by determining the carboxyl content, the carbonyl content and the viscosity of the oxidized rice starch obtained. Study showed that optimum conditions for the oxidation system were: using 0.4% (based on weight of starch [ows]) of H2O2 and a material:liquor ratio (M:L) of 1:6 at 60 °C for 4 h of UV irradiation. The produced oxidized rice starch was utilized as a sizing agent for cotton yarns. The sizing agent prepared (the oxidized rice starch) was evaluated by measuring the tensile strength (kg) and elongation at break (%) of the sized cotton yarns and determining of the percent of size removed from the sized cotton yarns by washing. Cotton yarns sized by oxidized starch used by Misr Company of Spining and Weaving in El-Mahalla El-Kubra was compared with the cotton yarns sized by our oxidized starch in terms of tensile strength, elongation at break and size removal (%). The results obtained were: 490 kg, 456 kg; 5.4%, 4.7%; and 86%, 55% for tensile strength, elongation at break and size removal (%) for cotton yarns sized by our oxidized starch and cotton yarns sized by oxidized starch used by the company, respectively. In other meaning our oxidized rice starch is competing with the oxidized starch used by the company.