Study On The Rheological Behavior Of Shellac Resin Salt

Shellac resin is a kind of green and renewable natural resin,which is widely used in the foo d and pharmaceutical indu stry.As a oligomer,the shellac-Na has a specific molecular structure.Its monomer is composed of hydrox yl fatty acids and shell acids,which are hydrophobic and hydrophilic.This oligomer with surfactant as monomer has specific static self-assembly beh avior in aqueous phase.Our group also used this assembly behavior to prepare a series of assembly materials from nanoscale microspheres to large-scale hydrogels.But at the same t ime,as a amphiphilic resin,its water-solubility is poor,so we need to m odify the shellac-Na to solve the problem of water solubility.Lac resin salt can be used as a drug coating material or as a film-forming agent in the food and pharmaceutical industry.But in production and processing,we will inevitably experience the tr eatment of dynamic shear field in water system,but the rheological behavior under dynamic shear field has not yet been accurately concluded.Based on this,this paper aims to study the rheological behavior of different types of lac resin salt in dynamic f low in the shear field,and then explore the lac resin salt molecules or interaction of aggregates in the shear field,and provide some theoretical support for the application of salt processing,lac resin.At the same time,it provides a preliminary basis for expanding the potential application potential of lac.The main contents and conclusions are as follows:?1?Prepare different concentrations of lac resin sodium salt?anion salt?,and then use a rotational rheometer to perform steady-state shear and d ynamic frequenc y scanning.The results showed that the shellac-Na showed shear thickening phenomenon under high shear,which was different from most shear thinning polymer linear viscoelastic materials.Steady shear test and dynamic frequency scanning of the shellac-Na and polyethylene glycol oxide?PEO?proved that the shear thickening of shellac resin sodium salt was caused by hydrophobic association of lac resin.After blending the the shellac-Na with pectin,it was found that the shellac-Na can change the rheological properties of water-soluble macromolecules from shear thinning to shear thickening,and has potential application as food thickener.?2?In order to analyze the rheological behavior of the sodium salt of the lac resin,make clear the contrib ution of the main components in the rheology.The main components of the shellac resin,the hard resin and the soft resin,were extracted from the granules by steps of water washing,ethanol dissolution,ether extraction,chloroform extraction,alkali extr action,acidification,and ethyl acetate extraction.Initially characterize the hard resin and soft resin according to the national standard,and prepare a sodium salt solution for rheological testing.The composition of the two resins was characterized by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.The results of rheological tests showed that shear resin thickening was found in the process of shearing,sodium salt and sodium salt of soft resin.During simulated creep,the viscosity of lac resin sodium salt was mainly supplied by hard resin,and elasticity mainly came from soft resin.EDC and NHS were used as coupling agents and catalysts to connect the free carbox yl group of the lac resin with ethylenediamine in the form of amide bond,and N-?2-amino ethyl?-lac resin amide was obtained.Infrared,DSC,TG,acid titration,MALDI-TOF-MS and other detection methods were used to characterize N-?2-amino ethyl?-lac resin amide and lac resin,proving that the content of carb ox yl group in the lac resin decreased and the amide bond was formed.Finally,the rheological test results show that the lac resin,ammonium salt,amide bond and hydrophobic properties of lac resin did not change the long chain part of the association will still be subjected to shear synthesis of clusters,as the increase in viscosity;stability of lac resin without ammonium salt sodium lac resin;ammonium salt is sodium lac resin it is easy to produce gel,in other words,the positive ion salt of lac resin than negative ion of salt stress is more sensitive to agglomerate.Finally,rheological tests on the shellac-NH₄ showed that the formation of the amide bond did not change the hydrophobic character of the long chain part of the lac resin,and the shear gr oup would still form a cluster,showing an increase in the viscosity.Finally,the rheological tests of lac resin ammonium salt showed that the formation of amide bond did not change the hydrophobic property of lac resin long chain part,and it was still s ynthesized by shear.