Stability of dilute water soluble phenol-formaldehyde resin solution

Key words:  water soluble phenol-formaldehyde resin  coagulation  turbidity  hydrodynamic diameter  zeta potential  colloid stability

Abstract:

The stability of a dilute phenol -formaldehyde resin solution was studied on in-house lab setup. When the concentration of the resin in distilled water varies from 50 to 250 mg L_l, 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 tuitidity of the system, the hydrodynamic diameter and the zeta potential of the resin molecular a^regate. 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, AIC13 and Na2S04 for the same resin solution is 1:0.026:0.00033 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 =s 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.