Mesoscopic Study On Konjac Glucomannan Interfacial Behavior And Characteristic

Polysaccharide is natural,non-toxic,renewable,green and safe,and konjac is widely used as a source of non-ionic polysaccharide.In the usability,the surfactants is usually present,and many properties of the mixed system are superior to any of the properties of a pure component system.The development of computer simulations,theoretical study is intensive and we summarize from the experimental rules to atomic,molecular-level research,in order to explain the mechanism of interaction at the molecular level.This article combines computer simulation and test methods to study the interaction of konjac glucomannan and surfactant in order to provide theoretical guidance and predict for the experimental design and application.The main contents and results are as follows:(1)We prepared KGM/anionic surfactant solution under different conditions,and analyzed the rheological properties,such as the viscosity,stress sweep,frequency sweep and temperature modulus curve,the mixed system still has the feature of shear thinning;with the concentration of sodium dodecyl sulfate increasing,the strength of generating aggregate increases,while the hoist of temperature will cause the system viscosity increased and then decreased.At low concentrations of KGM,the addition of surfactant made the system give priority to viscosity characteristics,and storage modulus is less than the loss modulus,internal friction increases,the interaction between molecules increased.(2)Dissipative particle dynamics is used to simulate the interaction of KGM and anionic surfactants,analysis of aggregation mechanism in the mesoscopic level,studied the effects of concentration,temperature and shearing on the structure and properties of the system.The simulation results show that some gaps of interface are filled by KGM,the total densities of the system increase.With the increasing of temperature,the density peak increases and moves left,but as the temperature continues to increase,the density peak will reduce again.Shear rate will affect the formation of aggregate.With the increase of surfactant concentration,the diffusion coefficient of the system is reduced firstly,and then concentration increased to a critical value,the diffusion coefficient increased rapidly,the viscosity decreased.Influence of temperature exaltation was the diffusion coefficient decreased firstly,then increased.This conclusion is consistent with the experimental result,this study also shows that this method is feasible.(3)Dissipative particle dynamics method is used to simulate the interaction between KGM and cationic surfactants,we focused on the concentration,temperature and shear effects on the structure and properties,and according to the simulation results,we speculated the mechanism of interaction.The simulation results show that with the increase of KGM concentration,the density peak will increase.The temperature made the densitypeak increased and moved rignt,but when the temperature rised to a certain value,the density peak decreased.At low shear rates,the density peak shifted to the right,and in the high shear rate conditions,the density peak decreased.During the simulation,high viscosity often mean to low diffusion,which makes the system is difficult to form a larger continuous phase zone.