Charge Number Effect On Interfacial Dilational Viscoelasticity Properties Of Surfactant

We are on the use of soap in the daily life many years ago,and the history of soap-making can not be verified.At the early era people have used fat,charcoal and carboniferous to prepare soap by azeotropic method.Over the past people use ash juice to wash oil commonly.In fact washing process itself is fat to the soap by saponification,so that it is the process of oil out of clothing.It has long been used as detergent saponins,and it is a kind of soap.With the development of science and production,people manufacture better "soap"-synthetic detergent,its species are increasing,and the scope of application is beyond the field of "washing".Such substances should not have been easy to "soap" and "detergent",but to "surfactant".Surface rheology is an important branch of rheology.It researches the flow and deformation of surface film under the external force.Surface deformation can be divided into two parts:surface dilatation and the surface shear.Compared to the surface shear,the research of surface dilatation becomes even more valuable.Because the theoretical and experimental results directly show that the surface dilatation of surfactant monolayer is much higher than the surface shear in recent years.Many scholars have repeatedly referred to the surface dilatation in the research of the stability of emulsion and foam.So the research on the dilatational viscoelasticity of interface or surface is significant to the research of the stability of emulsion and foam.This paper is mainly concerned with the research of dilatational rheological viscoelasticity properties of interface or surface film of different kinds of surfactants and surfactant/salt system by the interfacial dilatational viscoelasticity meter (JMP2000A),which is prepared by our laboratory and developed by Shanghai Powereach Co.Ltd.We get some information of the dilatational modulus,dilatational elasticity,dilatational viscosity,phase angle and other dilatational rheological viscoelasticity coefficients with sine wave movement methods,the same speed movement methods and interfacial tension relaxation methods and the influence of frequency,concentration to these coefficients.And thus we know the system table (circles) of the micro-mask type relaxation.In addition,the article also focused on various viscoelastic surfactant characters and the expansion of micro-relaxation process on the role of the different valence salts.The results of experiments indicate:(1) The dilatational modulus,dilatational elasticity,dilatational viscosity and phase angle of CTAB,SDBS and TritonX-100 are changed presentablely by frequency.The double logarithmic curve with dilatational modulus and dilatational frequency are an approximate linear,and both of the linear fit parameters are above 0.98.(2)Concentration has significant impacted to surfactant.The greater concentration of surfactant is,the smaller parameters of the expansion viscoelastic are. Because elements from the body opposite the proliferation of newly generated interface to add the elimination of the interfacial tension gradient has the dominant role.(3) Add salt can reduce the expansion viscoelastic parameters of surfactant.NaCl, CaCl₂ and LaCl₃ have different effect on surfactant.For TritonX-100,CaCl₂ has the greatest impact,and NaCl has the smallest.For SDBS,CaCl₂ is greater than NaCl.