NaCl对支链阳离子表面活性剂表面扩张流变性能的影响

Effect of NaCl on surface dilational rheological properties of branched cationic surfactant

为探讨无机盐对阳离子表面活性剂表面扩张流变性质的影响,利用悬挂滴方法研究了不同浓度支链阳离子表面活性剂十六烷基羟丙基季铵盐(C_(16)GPC)的表面扩张流变性质,考察了NaCl浓度对其动态及稳态弹性和黏性模量的影响趋势。结果表明:C_(16)GPC分子中的长支链在界面上的重排慢过程决定纯水溶液表面吸附膜的特性,表面膜以弹性为主,且强度较大,可高达70 mN/m左右;NaCl通过促进扩散交换影响表面膜的性质,少量的NaCl就能明显降低表面弹性和黏性模量。在0.1 Hz条件下,表面弹性和黏性模量只有纯水溶液的1/4左右;高NaCl浓度条件下,扩散交换过程控制表面膜性质,吸附膜以黏性为主。

In order to study the effect of inorganic salt on surface dilational rheological properties of branched cationic surfactant.The surface dilational rheological properties of branched cationic surfactant Guerbet hexadecylglycidyl ether ammonium chloride(C16GPC)were investigated by drop shape analysis.The influences of NaCl concentration on surface dilational elasticity and viscosity were expounded.It is found that the surface slow process involving re-arrangement of long branched alkyl chain determines the nature of adsorption film.The surface adsorption film is elastic in nature with a higher value about 70 mN/m.The addition of NaCl will accelerate the diffusion-exchange process,thereby affects the property of interfacial film.A small amount of NaCl has been shown to decrease sharply the surface dilational elasticity and viscosity to a quarter of their values for pure water at 0.1 Hz.The diffusion-exchange process controls the properties of film at higher NaCl concentration.As a result,the surface adsorption film behaves mainly viscous.