The role of 2-methyl-2,4-pentanediol modifier and its interaction with poly(vinyl butyral) binder in BaTiO3 and Li2O-B2O3-BaO-SiO2 glass suspensions

The role of the modifier, 2-methyl-2,4-pentanediol (MPD), and its interaction with poly(vinyl butyral) (PVB) binder with BaTiO3-based dielectric particles and Li2O-B2O3-BaO-SiO2 glass suspensions were investigated using viscosity and adsorption isotherm measurements, Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM). Commercial MPD and PVB commonly serve as a modifier and binder, respectively, in organic suspension media in low-temperature cofired ceramic (LTCC) fabrication processes. In the absence of a modifier, a suspension prepared with PVB behaves as a highly viscous fluid that is readily flocculated to form a get. This is due to the reaction of PVB hydroxyl groups with boron in the glass, as shown by FT-IR spectra. In suspensions prepared with MPD and PVB, the suspensions did not form a gel, and the B-OH peak in FT-IR spectra disappeared. This is because PVB binder interacts with MPD modifier, and this interaction between the binder and the modifier affects the rheology of the suspension and combined adsorption of PVB and MPD. Sequential studies of viscosity and adsorption show that the flow behavior of the suspension was independent of the addition sequence, and was primarily dependent on the presence of the modifier with high affinity and the reaction of the modifier with the binder species. (C) 2003 Elsevier B.V. All rights reserved.