Surface chemistry of lead titanate and its impact on binder removal

Carbon residue after binder burnout was characterized for several nonstoichiometric lead titanate powders, Thermal decomposition of the poly(methyl methacrylate) (PMMA) binder was performed in nitrogen at 600 degrees C, A drastic decrease in carbon retention was obtained in the case of the titanium-rich samples, The amount of carbon retention varies from 0.2 mg/m(2) to 1.2 mg/m(2) by changing the Pb/Ti molar ratio from 0.92 to 1.08, The surface reaction between PMMA and lead titanate particles 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, The 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 measurements, however, show that titanium-rich samples are more acidic, Thus, 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 indicated temperatures using nitrogen carrier gas as a model experiment, DRIFTS difference spectroscopy and Raman spectroscopy were performed on these samples after the exposure. MMA reacts with lead titanate powder 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 amount of sp(2) bonded carbon decreases with increasing exposure temperature.