二元阴离子型丙烯酰胺共聚物在二价金属离子存在下相分离行为的研究

水溶性丙烯酰胺类共聚物 ,作为粘度改性剂 ,在工业上已得到广泛应用 .特别近年来 ,它们大量应用于石油工业强化采油技术 ,引起了人们很大的重视1] .目前 ,这类用途的聚合物 ,主要在聚丙烯酰胺结构中 ,引入阴离子组分和不断增高产物分子量的方法 ,以提高聚合物溶液粘度和增粘效果 ,然而 ,在二价金属离子 (如Ｃａ2 + ,Ｍｇ2 + 等 )存在下 ,羧酸阴离子型丙烯酰胺类共聚物很容易络合发生沉淀 ,从而失去增粘作用2 ] .同时这类聚合物中酰胺基不稳定 ,易发生水解反应转化为羧酸基 ,并随温度升高而加剧3 ] ,因此在温度较高的应用条件下 ,二价金属…

STUDY OF PHASE SEPARATION BEHAVIOR OF BINARY ANIONIC ACRYLAMIDE COPOLYMERS IN THE PRESENCE OF DIVALENT METAL IONS

Phase separation behavior of the water soluble binary anionic acrylamide copolymer series (P3A) composed of non ionic monomer acrylamide (AM), weak acidic monomer acrylic acid (AA) and strong acidic monomer 2 acrylamido 2 methylpropanesulfonate (AMPS) was studied in the Ca 2+ ion aqueous solution. The P3A was found to exhibit an unusual phase separation behavior, which relates with structure and composition of the polymer, as well as the concentration and temperature in the dilute P3A solution. A non linear relationship appeared between the critical temperature T c of phase separation and the metal salt concentration with a minimum at the mid position, whereas the T c remains constant as varying polymer concentration. From comparison of the effects of AA and AMPS units on the phase separation behavior of P3A polymers the results obtained indicate that except for the difference in acidity of two anionic units, the phase separation is mostly affected by the structure of anion unites in the polymer chain. The AMPS units exhibit a good stability under the action of Ca 2+ ions due to their great steric influence of side chains compared to AA units. Therefore, containing more AMPS, the polymer (P3A) becomes the more resistant to phase separation in the divalent metal salt solution.