水溶性酚醛树脂稀溶液的稳定性

Stability of dilute water soluble phenol-formaldehyde resin solution

采过室内实验的方法考察了水溶性酚醛树脂稀溶液的稳定性。测试结果表明，在去离子水中，当酚醛树脂质量浓度为50-250mg·L^-1时，酚醛树脂分子聚集体的流体力学直径在6．5nm左右，其表面带负电，体系为透明溶液。随NaCl的加入，酚醛树脂分子聚集体的流体力学直径、ζ电势和体系浊度都发生变化。电解质对酚醛树脂溶液稳定性的破坏起主要作用，不同价态的阳离子作用不同，NaCl与MgCl2，AlCl3，Na2SO4的聚沉值比例为1：0．026：0．00033：0．49。pH〉7，体系中酚醛树脂聚集体的ζ电势较高，体系为透明溶液；pH=3．2为聚集体的等电点；pH〈3．2，酚醛树脂聚集体表面带正电，ζ电势较低，体系形成浑浊的悬浮体。

The stability of a dilute phenol-formaldehyde resin solution was studied on in-house lab setup. When the concen-tration of the resin in distilled water varies from 50 to 250mg·L^-1, the hydrodynamics diameter of the resin molecular aggregate is about 6.5 nm, the aggregate is negative charged and the solution is transparent. NaCl can change the turbidity of the system, the hydrodynamic diameter and the zeta potential of the resin molecular aggregate. The stability of the resin solution is governed by electrolyte and the affection varies with the covalence of the cations. The ratio of critical coagulating concentration （CCC） of NaCl to MgCl2 ,AlCl3 and Na2 SO4 for the same resin solution is 1 ： 0. 026： 0. 000 33： 0.49. pH is able to affect the stability of the resin solution, pH 〉 7, the aggregate is negative charged with a high zeta potential, which makes the solution transparent and stable, pH = 3.2 is the isoelectric point of the aggregate, pH 〈 3.2, the aggregate is positive charged with a low zeta potential, so the solution is unstable and turns to be a turbid suspension.