Synthesis And Characterization Of Blood Volume Expander Hydroxy Ethyl Starch 200/0.5

Hydroxyethyl starch 200/0.5(HES200/0.5)is a kind of plasma products most widely used recently.In this paper,waterborne method was used to prepare hydroxyethyl starch,and the preparation procedure of hydroxyethyl starch 200/0.5 was studied systematically,including:1)the etherification of branched chain,namely graft hydroxyethyl group on the corn starch;2)the hydrolysis of hydroxyethyl starch;3)refining process,including post-processing and drying process.After the preparation procedure,the structure of HES200/0.5 was characterized by FT-IR,1H-NMR,13C-NMR and the molecular weight and molecular weight distribution,molar substitution degree,C2/C6 ratio,sodium chloride content and intrinsic viscosity of HES200/0.5 were also tested.HES200/0.5 was then characterized systematically.Firstly,the branched chain corn starch was used as raw material and with the ethylene oxide as catalyst,etherificating took place,which means that the hydroxyethyl group was grafted on the corn starch under alkali condition.This progress mainly studied the effects of several factors on the molar substitution degree and C2/C6 ratio of the products,including the temperature,the amount of catalyst,the amount of alkali,and reaction time,etc.The results showed that the suitable molar substitution degree and C2/C6 ratio could be acquired,with the amount of the ethylene oxide being 18g,alkali being 4g,etherification temperature being at 35? and the time being 6h.Then,to break up the bonds of high molecular weight hydroxyethyl starch during the hydrolysis reaction,and the concentrated hydrochloric acid was used as a catalyst.Orthogonal experiments were carried out to study the conditions that affect the hydrolysis reaction of branched chain corn starch.We also studied the effects of reaction parameters on the hydrolysis reaction time,including the solution concentration,the temperature,the acidity and the stirring rate,etc.Finally the solution concentration(w/v)was decided as 35%,with the temperature 75?,the acid concentration 0.072mol/L,and the stirring rate 400r/min,in order to attain suitable hydrolysis reaction time.By analyzing the relationship between kinematic viscosity and molecular weight,we found the obvious linear relationship between kinematic viscosity and molecular weight during the hydrolysis progress.The molecular weight would satisfy the requirement,when the kinematic viscosity was controlled among 21?24 mm2/s.Finally,self-regulating HES200/0.5 was characterized systematically,and the results proved that the structure of self-regulating HES200/0.5 was correct,with satisfactory molecular weight,and narrow molecular weight distribution.Besides,other important indexes such as molar substitution degree,C2/C6 ratio,sodium chloride content and intrinsic viscosity of HES200/0.5 also met the requirement.