支链烷基苯磺酸钠溶液的界面扩张流变性质

Interfacial dilational rheological properties of branched-alkyl benzene sulfonate solutions

为了更加深入地了解烷基支链化对烷基苯磺酸钠界面扩张流变性质的影响,通过滴外型分析法,研究了十六烷基-2-苯磺酸钠(2-Ø-C_(16))、十六烷基-4-苯磺酸钠(4-Ø-C_(16))、十六烷基-6-苯磺酸钠(6-Ø-C_(16))和十六烷基-8-苯磺酸钠(8-Ø-C_(16))4种不同支链化程度的烷基苯磺酸盐溶液的界面扩张流变性质,考察了吸附时间、振荡频率、溶液浓度对界面扩张弹性模量和粘性模量的影响。结果表明:4种支链烷基苯磺酸钠都有较强的界面活性;除6-Ø-C_(16)外,其他支链烷基苯磺酸钠在较宽的浓度范围内,慢弛豫过程控制界面膜性质,而高浓度条件下扩散交换过程起主导作用;支链化程度较大的烷基苯磺酸钠分子尺寸较小,向界面扩散的速度更快,同时油分子的插入削弱了支链烷基苯磺酸钠分子链间的相互作用,界面扩张弹性明显降低;此外,支链化程度的增大使支链烷基之间的相互作用产生的弛豫过程增强,扩张粘性增大。

To deeply understand the effect of branching of alkyl chain on the interfacial dilational rheological properties of sodium alkyl benzenesulfonate,the interfacial dilational rheological properties of four alkyl benzene sulfonates with different branched degree,including hexadecyl-2-benzene sulfonates(2-Ø-C_(16)),hexadecyl-4-benzene sulfonates(4-Ø-C_(16)),hexadecyl-6-benzene sulfonates(6-Ø-C_(16))and hexadecyl-8-benzene sulfonates(8-Ø-C_(16))have been investigated by drop shape analysis method.The influences of adsorption time,oscillating frequency and bulk concentration on the interfacial dilational elasticity modulus and viscosity modulus were expounded.The experimental results show that four kinds of sodium branched alkyl benzene sulfonates have high interfacial activities.In a wide range of concentration,the slow relaxation process controls the properties of the interfacial film,while the diffusion exchange process plays a dominant role under high concentration conditions except for 6-Ø-C_(16).The alkyl benzene sulfonate with higher branching degree has smaller molecular size,which accelerates the diffusion-exchange process.At the same time,the interfacial interactions among the molecular chains of sodium branced alkyl benzene sulfonates were weakened by the intervening oil molecule.As a result,the dilational elasticity decreases obviously with an increase of branching degree.On the other hand,the dilational viscosity increases,since the increase in the degree of branching enhances the relaxation process generated by the interaction between brached alkyl groups.