Effect of glass transition temperature of polymers on rheological behavior of alumina suspension and properties of alumina green sheets

Abstract

The effect of binder systems having the same glass transition temperature (Tg) on rheological behavior and properties of green sheets was investigated in this study. Four polymers were produced by changing the ratio of three monomers, n-BMA (n-Butyl Methacrylate), 2-EHMA (2-Ethyl Hexyl Methacrylate) and MAA (Methacrylic Acid). Tg of polymers were 20.2, 7.1, -2.6 and -9.9 degrees Celsius in a calculation respectively. DOP (Dioctyl Phthalate) was added to former three polymers in order to adjust Tg to -9.9°C degree Celsius by coordinating quantity of addition. These polymers were used as binders for alumina green sheets. As a result, all of the suspensions showed Newtonian Flow behavior, and the quantities of adsorbed polymer to alumina particles were almost the same. The packing degrees of green sheets were more than 58 mass%. As the quantity of DOP in binders increased, the packing degree of green sheet decreased. The tensile stress and strain of green sheets were almost the same value. Judging from thermal decomposition analysis, it was found that the temperature at 50 mass% loss of organic compounds in green sheets were lower than temperature at 50 mass% loss in polymer sheets. In four green sheets, as for the green sheet containing much quantity of DOP, maximum thermolysis speed was observed at the lowest temperature.