THERMOGRAVIMETRY MASS-SPECTROMETRY ANALYSIS OF THE PROCESS FOR REMOVING BINDER POLYMER FROM CERAMICS OBTAINED BY INJECTION-MOLDING

A combined thermogravimetry/mass spectrometry (TG/MS) system has been used to analyze the evolved gases from disks consisting of binders and zirconia in both inert and oxidizing atmospheres in order to clarify the removal process of the binders. Polybutyl methacrylate (PBMA) and linear low density polyethylene (LLDPE) were used as the main binders for ceramics obtained by injection molding, because they were easily r emoved from the product before sintering. In an oxidizing atmosphere, PBMA degraded to a monomer, whereas LLDPE degraded to low molecular we ight hydrocarbons, carbon dioxide and water in two steps. The effect o f the binders on the resulting cracks in the disk was interpreted in t erms of the volume of evolved gases.