(487a) Effect of Supports On the Catalytic Hydrogenation of Polystyrene

Fully saturated hydrocarbon polymers are technologically and commercially important materials, which exhibit superior stability toward thermal, oxidative, and hydrolytic degradation. The heterogeneous catalytic hydrogenation of polystyrene (PS) dissolved in cyclohexane have been investigated in a batch reactor over Pt-, Pd-, and Ni-containing catalysts. Ultra violet (UV) technique was employed to monitor the hydrogenation degree. The catalyst properties were modified by sol-gel methods, which produced catalyst with well-defined surface basicity and active site distribution. The effects of temperature, hydrogen partial pressure, agitation speed, and catalyst support were investigated over the ranges from 138 to 190 °C and 500 to 1500 psi. In each case fully saturated materials were obtained with no chain scission (i.e., degradation). The rate of hydrogenation showed strong dependence on the catalyst support. The dynamic properties of these materials were investigated using differential scanning caloimetry (DSC). Saturated polystyrene, denoted poly(vinylcyclohexane) (PVCH), exhibited a glass transition temperature (Tg) that is ~40 oC higher than polystyrene.

Acknowledgments

This work was supported by King Abdulaziz City for Science and Technology under Grant (AT-27-3).