SURFACE-CHEMISTRY OF LEAD TITANATE AND ITS IMPACT ON BINDER REMOVAL

Carbon residue after binder burnout was characterized for several nons toichiometric lead titanate powders, Thermal decomposition of the poly (methyl methacrylate) (PMMA) binder was performed in nitrogen at 600 d egrees C, A drastic decrease in carbon retention was obtained in the c ase of the titanium-rich samples, The amount of carbon retention varie s from 0.2 mg/m(2) to 1.2 mg/m(2) by changing the Pb/Ti molar ratio fr om 0.92 to 1.08, The surface reaction between PMMA and lead titanate p articles was studied by diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS), Surface hydroxyls reacted with ester groups in the PMMA or the methylmethacrylate monomer produced upon pyrolysis, T he DRIFTS results showed that titanium-rich samples are less reactive and produce less surface-bound organic groups, Interestingly, titanium -rich samples contained more surface hydroxyls, Isoelectric point meas urements, however, show that titanium-rich samples are more acidic, Th us, the reactivity of the surface hydroxyls is determined primarily by their acid-base characteristics rather than their concentration, Lead titanate powder was exposed to MMA vapor in a tube furnace at the ind icated temperatures using nitrogen carrier gas as a model experiment, DRIFTS difference spectroscopy and Raman spectroscopy were performed o n these samples after the exposure. MMA reacts with lead titanate powd er in manner similar to PMMA, Analysis for sp(2) and sp(3) absorbance of Raman spectra of these exposed powders at 400 degrees-600 degrees C showed pyrolysis behavior of surface-reacted species. The relative am ount of sp(2) bonded carbon decreases with increasing exposure tempera ture.