部分水解聚丙烯酰胺溶液的界面扩张流变特征

Dilational interfacial properties of PHPAM solutions

借助于界面扩张流变测量方法,研究了测量时间对超高分子量聚丙烯酰胺Mo 4 0 0 0溶液与十二烷形成界面的黏弹性特征;研究了Mo 4 0 0 0溶液浓度对界面扩张黏弹模量E的影响,探讨了Mo 4 0 0 0溶液与空气、十二烷、原油所形成界面的E特征.结果表明,同一浓度的Mo 4 0 0 0溶液与十二烷形成的E大小随测量时间而变化,初期E较小,随着测量时间的增长而逐渐增大直至达到平衡.在同一测量时间时,Mo 4 0 0 0溶液浓度愈大E愈大,达到平衡E的时间愈短.不同浓度时,初始E的差异大于平衡E的差异.由于Mo 4 0 0 0的黏均分子量高达2 .2×10 7,故弹性模量E′对E的贡献大,虽然随着溶液浓度的增大,黏性模量E″对E的贡献比例略有上升,但是弹性模量E′对E的贡献仍为主导.此外,Mo 4 0 0 0溶液与不同物质所形成的不同界面具有不同的黏弹性特征,与空气、十二烷、原油所形成界面的E的大小次序为E空气>E十二烷>E原油,即E的大小随两相密度差的减小而减小.

The changes of interfacial viscoelasticity with measuring time and the effect of PHPAM concentration on viscoelasticity at the interface between PHPAM Mo-4000 and dodecane were investigated by means of dilational method. Preliminary comparison experiments were also done for different interfaces such as air/PHPAM, dodecane/PHPAM, and crude oil/PHPAM. The results show that interfacial viscoelasticity increases while the testing time lasting with the same PHPAM concentration. The viscoelasticity is smaller at beginning and becoming larger with the time increaseing until the equilibrium state is obtained. The larger the PHPAM concentration, the higher the initial and equilibrium viscoelasticity are at dodecane/PHPAM interface and the shorter the time needed to reach the equilibrium state is. The difference of initial viscoelasticity is larger than that of the equilibrium viscoelasticity for different concentrations. The oscillation experiments show that elastic modulus (E′) contributes to viscoelasticity (E) much more than viscous modulus (E″). Although the contribution of E′ decreases with the increment of PHPAM concentration, it still plays a main role in the viscoelasticity modulus for the high molecular weight of PHPAM Mo-4000. Moreover, among those three experimented interfaces, viscoelasticity modulus at air/PHPAM surface is the largest one. That at dodecane/PHPAM interface is the second. That at crude oil/PHPAM interface is the smallest. It seems that viscoelasticity between two phases lessens when the difference of density between these two phase decreaseing.