Chinese Journal of Applied Chemistry ›› 2010, Vol. 27 ›› Issue (02): 227-230.DOI: 10.3724/SP.J.1095.2010.90142

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Influences of Fe2+/H2O2 on Colloidal ζ Potential and Stability of Urea-Formaldehyde Resins

GUO Li-Ping, LIU Ming, LEI Jia-Heng*, DU Xiao-Di, SHI Heng-Xin   

  1. (Department of Chemistry,Wuhan University of Technology,Wuhan 430070)
  • Received:2009-03-02 Revised:2009-05-19 Online:2010-02-10 Published:2010-02-10
  • Contact: LEI JiaHeng

Abstract:

The influence of  Fe2+ /H2O2 on colloidal ζ potential and stability of  Urea-Formaldehyde (UF) resins were studied by means of colloidal chemistry method. The results show that the average ζ potential of urea-formaldehyde colloidal particles is about -32.5mV  at a pH value of 8.0 and they exist in monodisperse state. The ζ potential is decreased  rapidly with the addition of ferrous ions or hydrogen peroxide. As the exclusion barrier decreases, colloidal particles begin to aggregate, viscosity also increases and UF resin eventually gels. However, the influence of hydrogen peroxide on ζ potential and the viscosity η of  UF colloidal particles are much less than the ferrous ions. pH value plays an important role in keeping the stability of the colloidal particles, When pH≈9, the system has the biggest ζ potential, besides , the absolute values of ζ potential reduce rapidly by either increase or decrease of pH value, when pH>9 the absolute value of ζ potential declines even more significantly. The mechanism of  Fe2+ /H2O2 affecting the stability of  UF adhesive was discussed based on colloidal electric double layers theory.

Key words: urea-formaldehyde resin, colloidal stability, ferrous ion, hydrogen peroxide, ζ potential

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