Study On Rheological Properties Of Hydroxyethyl Cellulose In Aqueous Solution

Hydroxyethyl cellulose(HEC),which is non-ionic and water-soluble cellulose ether,is of big yield,rapid development and has been widely applied in various fields.The nature of HEC is different due to the different molar substitution degree of HEC.HEC of low molar substitution degree can be dissolved in a dilute alkali solution.On the other side,HEC of high degree of substitution is soluble into water.The structural change of HEC molecular chain in solution causes the change of solution viscosity which could affect the HEC application in various areas.Therefore,the study of relationship between the solution properties of HEC and HEC molecular structure in the solution can provide reasonable theory foundation for the HEC applications.In this paper,two kinds of HEC were refined,which structure were characterized by IR spectroscopy and NMR.The molecular weight of HEC was determined by GPC.Through calculation,the molar substitution degree of HEC with lower viscosity is about 1.7,and the molar substitution degree of HEC with higher viscosity is about 3.4.It is concluded that the main reason for the difference of the solution viscosity of the two kinds of HEC with same concentration is the difference of molar substitution degree of HEC.By testing the viscosity of the two kinds of HEC solution at 25 ? with various melting temperatures from 40 ??90?,it was found that the solution temperature have effects on the viscosity of HEC solution.Through the determination of the viscosity for these two kinds of HEC solution at 25 ? with different aging time,it was revealed that the aging time has some effect on the viscosity of the solution.The effect of viscosity of HEC solution was not same due to the different molar substitution of HEC.For HEC with low molar substitution degree,the viscosity of solution was decreased with the increase of aging time.In its dilute solution and semidilute solution area,the viscosity of the solution is not affected by the solution temperature;in the region of the concentrated solution,the viscosity of the solution was decreased with the increase of solution temperature.For HEC with high molar substitution degree,the viscosity of solution did not change along with the increase of aging time.In the area of its dilute solution,the viscosity of the solution did not change with the increase of solution temperature;in the semidilute and concentrated solution area,the viscosity of the solution was reduced with the increase of solution temperature.The particle size of the HEC solution was tested by dynamic light scattering to explain the above phenomenon from the angle of molecular conformation.In addition,the nature of the viscosity of the blend solution of HEC and tamarind polysaccharide(TSP)was also studied in this dissertation.It was observed that the blend solution exhibited the similar characteristics of HEC solution.This finding has certain theoretical significance for the practical application of HEC and TSP.