Effect of polyethylenimine on hydrolysis and dispersion properties of aqueous Si3N4 suspensions

Xinwen Zhu, Tetsuo Uchikoshi, Tohru S. Suzuki, Yoshio Sakka

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

The roles of polyethylenimine (PEI) in the hydrolysis and dispersion properties of aqueous Si3-N4 suspensions were studied in terms of the hydrolysis, adsorption, electrokinetic, and rheological measurements. It was found that the pH change of the suspensions in the acidic environment could be minimized in the presence of ≥ 0.5 dwb% PEI. The ammonia and oxygen measurements suggest that this phenomenon is primarily attributed to the buffer mechanism generated by the ionized PEI, instead of the protection mechanism. The constant pH enables the suspensions to retain a better stability with time at acidic pH. The adsorption of PEI on Si3N4 is a high-affinity type at highly basic pH, but is a low-affinity type at acidic pH. As the PEI amount increases, the adsorption shifts the isoelectric point (IEP) of Si3N4 from pH 5.9 to pH ∼11 until complete coverage is attained. The stability of Si3N4 suspensions is found to depend strongly on the saturated adsorption of PEI, which is as a function of the pH and PEI amount. Once the saturated adsorption limit is reached, the excess free PEI molecules become more detrimental to the stability with increased solid loading. The stabilization mechanisms of Si 3N4 suspensions by PEI were discussed in detail.

Original languageEnglish
Pages (from-to)797-804
Number of pages8
JournalJournal of the American Ceramic Society
Volume90
Issue number3
DOIs
Publication statusPublished - 2007 Mar 1

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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