The Synthesis Of Hydroxyakylation Starch And The Study Of Its Properties

The thesis consists of the following two parts:Part I: Development and application of potato starch and modified starch.This part gives an introduction of the peculiar properties and the current application of potato starch, modified starch and its derivations in industrial field; points out the significance of the applied research on potato starch and modified starch for the development of potato industry; analyses the strong points and weaknesses that hydroxyakylation starch has in production and application as following: hydroxyakylation starch has stability when faced with acid, alkali, oxidizing and hydrolyzing etc., and its tempreture of pasting is low, it has good properties in pasting and membranizing, while the development of hydroxyakylation starch is limited to the development of hydroxyethyl starch and P-hydroxypropane starch. And the paper also points out from the chemical perspective that the new-typed hydroxyakylation potato starch has the bright future in its synthesis and applied research. The reaction between starch and halide alcohol can synthetize hydroxyakylation starch, for instance, the combination of fair qualities of potato starch and hydroxyakylation starch has a tendency to form good hydroxyakylation starch with the compound variation of cross-link and hydroxidization.Part II The synthesis of hydroxyakylation starch and the study of its propertiesThree new kinds of hydroxyakylation starch have been synthesized under the following conditions: potatoes are used as materials, NaOH as the catalyst, the ring clereage products as circle-ether, alcohol as reaction medium. And the tests of properties are conducted on the temperature of pasting, viscosity, the warm stability of viscosity , solubility of cool water and membranizing. And the results indicate that the properties of three kinds of hydroxyakylation starch are similar to the good properties of hydroxyethyl starch. The potato glycerin starch has the lower temperature of pasting , higher viscosity and warm stability of viscosity, greater solubility of cool water and better membranizing and they have better practical prospect compared with hydroxyethyl starch. The results of property tests also show that the components of etherifying agent have the regular effects on hydroxyethyl starch ; while the numbers of hydroxy group increase, the temperature of pasting decreases, viscosity increases and solubility of cool water increases significantly. When there is only one hydroxy group, the distance between hydroxy group and oxygen atoms of ethery band is farther and the pasting temperature of the products is lower, and viscosity is higher. As far as the manufacture of potato starch, a group of optimized reaction conditions of manufacturing glycerin starch has been established through positive crossing tests and statistical analysis, that is, in alcohol, the dose of the catalyst: 12%; dose of etherifying agent 18%, reaction temperature 45癈; reaction duration 17h; concentration of starch emulsion: 20%. Under this condition, the average etherifying degree is 0.127. The statistical analysis have indicated that the reaction temperature has the strongest effect on etherifying degree among the four factors.