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Interactions of Organic Additives with Boric Oxide in Aqueous Barium Titanate Suspensions
Author(s) -
Li ChiaChen,
Jean JauHo
Publication year - 2002
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2002.tb00294.x
Subject(s) - aqueous solution , dispersant , boric acid , ethylene glycol , ethylene oxide , chemistry , suspension (topology) , polymer chemistry , dilatant , materials science , chemical engineering , inorganic chemistry , organic chemistry , copolymer , composite material , polymer , dispersion (optics) , physics , mathematics , homotopy , pure mathematics , optics , engineering
The interactions between added boric oxide (B 2 O 3 ) and organic additives, and their effects on the colloidal stability of aqueous BaTiO 3 suspensions have been investigated. The initially Newtonian or pseudoplastic aqueous BaTiO 3 suspension with poly(vinyl alcohol) (PVA) becomes dilatant, and its viscosity also increases dramatically when a critical amount of B 2 O 3 , 0.4 wt%, is added. This has been attributed to a chemical reaction between the dissociated borate ion (B(OH) 4 − ) and PVA, which form a gel‐type structure in the aqueous BaTiO 3 suspension. The dilatancy and viscosity of the aqueous BaTiO 3 suspension with PVA and B 2 O 3 increase significantly when a dispersant of ammonium salt of poly(acrylic acid) (PAA‐NH 4 ) is present. The ionization of B 2 O 3 is enhanced by the basicity of dissociated PAA − , promoting the formation of PVA‐B(OH) 4 − gel‐type structure in the aqueous BaTiO 3 suspensions. With added plasticizer of 1,2‐ (e.g., ethylene glycol (EG)) or 1,3‐diol (e.g., 1,3‐propanediol (PPDL)) molecular structure, both the dilatancy and viscosity of aqueous BaTiO 3 suspensions with PVA, B 2 O 3 , and PAA‐NH 4 decrease dramatically. Stable compounds of diol‐B(OH) 4 − are formed before the dissociated B(OH) 4 − reacts with PVA, reducing the degree of gelation of aqueous BaTiO 3 suspensions. A stability map is constructed to describe the amount of EG required to obtain colloidally stable aqueous BaTiO 3 powder suspensions with PVA, PAA‐NH 4 , and B 2 O 3 .