烷基季铵盐体系泡沫性能与表面性质研究

Study on relationship between foam properties and surface properties of alkyl quaternary ammonium salts system

使用德国KRSS公司生产的DSA100界面扩张流变仪,采用小幅低频振荡法研究阳离子表面活性剂十二烷基三甲基氯化铵(LTAC)、十四烷基三甲基氯化铵(TTAC)、十六烷基三甲基氯化铵(CTAC)和十八烷基三甲基氯化铵(OTAC)的泡沫性能与表面性质的关系。结果表明:起泡剂浓度低于其临界胶束浓度(CMC)时,起泡性、稳定性和表面张力随着活性剂浓度的增大而增强,达到CMC后则基本不再变化;起泡剂的疏水链越长,其起泡性和稳定性越差,体系的表面张力也逐渐增大;在LTAC、TTAC、CTAC和OTAC体系的扩张流变性质当中,弹性模量居主导地位,并且弹性模量会随工作频率的增加而增大,随着浓度的增大出现一个极大值,随着疏水链长的增加而减小,而黏性模量则始终很小;泡沫的起泡性由表面张力和表面黏弹性等多个参数共同决定,而弹性模量与泡沫的稳定性具有明显的线性关系。

The relationship of foam properties and surface properties of cationic surfactant of dodecyl-trimethyl ammonium chloride（ LTAC）,tetradecyltrimethyl ammonium chloride（ TTAC）,hexadecyltrimethyl ammonium chloride（ CTAC）,and octadecyltrimethyl ammonium chloride（ OTAC） were studied through the small amplitude low-frequency method using the DSA100 interfacial expansion rheometer made by the Germany KRSS company. The results show that when the concentration of the foaming agent is lower than its critical micelle concentration（ CMC）,the foam ability,stability and surface tension are enhanced with the increased surfactant concentration,and no longer change after the CMC is reached. With the increasing hydrophobic chain of foam agent,the foam ability and stability decline,and the surface tension goes up. Among the expansion rheological properties of the LTAC,TTAC,CTAC and OTAC system,the elastic modulus is dominant. Also,the elastic modulus inclines with the increasing working frequency. And a maximum of the elastic modulus comes out with the increasing concentration. The elastic modulus reduces with the increasing hydrophobic chain,while the viscous modulus keeps small all along. The foam ability of the foam is determined jointly by several parameters,such as surface tension and surface viscoelasticity,etc. Meanwhile,the elastic modulus and the stability of the foam show a significant linear relationship.