Studies of interfacial interactions between petroleum acids and associating polyacrylamide by dilational rheological measurements

In the present work, the interfacial dilational properties of hydrophobically modified polyacrylamide (HMPAM) at the kerosene/water interface were investigated by means of drop shape analysis method. The influence of petroleum acids on the dilational rheological behavior of HMPAM was expounded. The experimental results show that the dilational modulus of HMPAM layer can arrive at a high value of 80 mN/m for 2000 ppm polymer solution due to the formation of interfacial net structure by interactions among hydrophobic blocks of different HMPAM molecules. The petroleum acids molecules can interact with the hydrophobic blocks of HMPAM and form mixed micelle-like associations at interface, which will produce new fast relaxation process involving exchange of acid molecules between interfacial aggregates and free monomer at low HMPAM concentration, and destroy the interfacial net structure at high HMPAM concentration, respectively. Therefore, the moduli of HMPAM decrease obviously after adding petroleum acids, especially at higher HMPAM concentration. [GRAPHICS] .