Abstrato

Grafting onto carbohydrate polymer using novel potassium persulphate/tetramethylethylene diamine redox system for initiating grafting

Kh.M.Mostafa, Abdul Rahim Samarkandy, A.A.El-Sanabary

Starch as one of the most abundant, renewable, low cost and biodegradable carbohydrate polymers world wide, suffers fromsome drawbacks, the most outstanding is a lakes of properties of synthetic polymers. So, modification of starch by graft co polymerization will provide a substantial modification route to alter physical and chemical properties of starch thereby enlarges the range of its utilization. by attaching a flexible synthetic polymer onto the rigid natural polysaccharides backbone without greatly changing the latter. In addition to the main disadvantageous of the above technique are the high % of homopolymer and lower % grafting. At this point, our research team directed the work towards how to maximize the graft yields and graft reaction efficiency % and minimize to lower extent the homopolymer % as well as enhancing the water solubility of the prepared copolymers. Based on the results obtained, appropriate conditions for graftingMAAonto pregelled starch were established and the graft yield is higher under the following conditions: using 10mmol/L potassiumpersulfate, 8mmol/L TMEDA, 50% MAA concentration (based on weight of substrate), liquor ratio, 10, reaction time, 60min; and polymerization temperature, 60ï‚°C.On the other hand, grafting enhanced significantly by adding Fe3+, Cu2+ and Li1+in the grafting media and follows the order Fe3+> Cu2+> Li1+, in addition to the solubility%. Approximately 37.5%graft yield and 75%graft reaction efficiency as well as 25%homopolymerizationwere obtained whenmethacrylic acid was graft co polymerized onto pregelled starch as a reactive carbohydrate polymer using a newredox initiation systemnamelyKPS / TMEDAredox pair. Grafting was also enhanced significantly by adding Fe3+, Cu2+ and Li1+in the grafting media and follows the order Fe3+> Cu2+> Li1+. Furthermore, notable enhancement in solubility%of grafted samples with lower graft yields than that of higher one.