无机盐对部分水解聚丙烯酰胺溶液黏度影响的实验与理论研究

采用实验与分子动力学模拟(MD)结合的方法研究无机盐对部分水解聚丙烯酰胺(HPAM)溶液黏度影响的规律及微观机制。结果表明:无机盐对溶液黏度影响较大,其中Ca Cl2和Mg Cl2对溶液降黏作用强于Na Cl,且当Ca Cl2和Mg Cl2浓度相同时Mg Cl2的降黏作用更加明显;当溶液中加入无机盐时,由于盐离子与聚合物中羧酸根基团的静电吸引,使其在聚合物周围形成阳离子层,从而减弱了聚合物分子链上羧酸根基团之间的排斥作用,导致分子链收缩,进而降低溶液的黏度;相比于Na+和Ca2+,Mg2+更易靠近HPAM分子链,对分子链构型及黏度的改变更加明显。

Experimental and theoretical study of the inorganic salts influence on the viscosity of partially hydrolyzed polyacrylamide in aqueous solution

Molecular dynamics simulations and experiments were performed to study the influence of inorganic salts on the viscosity of partially hydrolyzed polyacrylamide (HPAM) in solution. The results show that the inorganic salts present large influence on the viscosity of the solution. And in the aspect of reducing viscosity, the effect of CaCl₂ and MgCl₂ is stronger than that of NaCl. Furthermore, MgCl₂ was more effective than CaCl₂ at the same concentration. It is also found that cations would interact with carboxylate radicals in HPAM through electrostatic attraction, through which the cation layer can be formed around HPAM. As a result, the rejection effect among the carboxylate radicals in HPAM was reduced, which leads to the shrink of the molecular chain of HPAM and affect the viscosity of the HPAM solution. Compared to Na^+and Ca²⁺, Mg²⁺ is much closer to HPAM molecules, which shows more effect on the change of configuration and viscosity of HPAM.