Preparation And Characterization Of Starch Acetate And Starch Octenylsuccinate In Ionic Liquid AMIMCl

Starch is a natural polysaccharide,one of the most widely sourced polymer compounds on the earth,which is a natural green bio chemical resource.It is of a natural green bio chemical resource.Through esterification,starch not only retained the hydrophilicity of starch skeleton,but also increased the lipophilicity.Ionic liquid is a green solvent discovered in recent ten years.Among them,1-allyl-3-methylimidazole chloride?AMIMCl?ionic liquid has a good solubility to corn starch?CSt?.In order to explore the rules of starch esterification in CSt-AMIMCl system and the influence on the products,the following research contents were carried out in this paper:?1?The effects of AMIMCl on the structure and physicochemical properties of CSt.Using CSt as raw material and AMIMCl as solvent,corn starch homogeneous mixture system was constructed.The rheological properties of CSt-AMIMCl homogeneous solution were measured by HAAKE rheometer.The molecular structure,crystal structure and thermal behavior of CSt and AMIMCl treated regenerated corn starch?RCSt?were characterized by TGA-DSC,RVA and TGA-FTIR.The rheological and thermal behaviors of CSt and AMIMCl at different mass fractions and temperatures were explored.The results showed that CSt-AMIMCl was a pseudoplastic fluid with a certain thixotropy in the range of 1%?8%starch mass fraction,and the homogeneous system could not be formed when the mass fraction of CSt exceeded 8%.The thermal decomposition temperature of RCSt was lower than that of CSt,which indicated that AMIMCl could weaken the molecular chain of starch and activate the activity of CSt reaction to a certain extent.The results provide experimental basis for the esterification of corn starch in AMIMCl.?2?Preparation and characterization of AACSt in AMIMCl medium.Using CSt as raw material,acetic anhydride?AA?as denaturation reagent and AMIMCl as solvent,the homogeneous reaction system of CSt-AMIMCl-AA was constructed.The preparation process of AACSt without catalyst was investigated by single factor test.The rheological characteristics of AACSt were studied by HAAKE rheometer,TGA-DSC,FTIR,XRD and SEM characterization of sex and structure.The results showed that AACSt in CSt-AMIMCl-AA system has the best preparation conditions:esterification temperature 90?,esterification time 2.5h,molar ratio of AA to starch dehydrated glucose unit?AGU?5,CSt mass fraction 6%,under which the degree of substitution of AACSt is 1.517.The rheological analysis showed that AACSt paste belongs to pseudoplastic fluid.The thermal stability of AACSt was lower than that of CSt.In nitrogen atmosphere,the main process of AACSt pyrolysis was dehydration and decarboxylation.The FTIR results showed that there was a characteristic absorption peak of-OCOCH₃in AACSt,indicating that the acetylation reaction between CSt and AA did take place;the XRD pattern showed that AACSt was amorphous structure;the SEM photos showed that AACSt no longer had independent particles,and the particles had adhered to each other.?3?Preparation and characterization of starch octenylsuccinate?OSACSt?in AMIMCl medium.CSt-AMIMCl-OSA homogeneous reaction system was constructed with CSt as raw material,octenyl succinic acid?OSA?as denaturant and AMIMCl as medium.Through single factor experiment,the preparation conditions of OSACSt were explored,and the product structure,thermal characteristics and emulsification characteristics were analyzed.The best preparation conditions of OSACSt were as follows:the mass fraction of CSt was6%,the esterification time was 2 hours,the esterification temperature was 90?,the molar ratio of OSA and AGU can be selected in the range of 0.03?0.24according to the degree of substitution.FTIR analysis showed that CSt has successfully reacted with OSA;XRD and SEM showed that the obtained OSACSt was a fine particle agglomerate without definite morphology;TGA-FTIR test showed that the OSA group in OSACSt can be stabilized to 200?in nitrogen atmosphere;polarizing microscope?POM?showed that the OSACSt prepared in AMIMCl medium was an excellent macromolecular emulsifier.