Rheological properties of polystyrene degraded by mechanical forces

Abstract

Polystyrene was degraded by using a vibrating ball mill. The viscosities of the degraded products were measured by using a capillary viscometer, and the molecular weights were determined. It was found that the viscosities and the molecular weights of the degraded polystyrene decreased as the degradation time and the energy input for degradation increased. These facts were explained by the fracture of long polymer molecules into shorter molecules. These experimental results for the rheological phenomena of the degraded products were analyzed by applying the Ree-Eyring equation for viscous flow. The parameters $x_2/α_2, β_2$ and $x_1 β_1/α_1$ in the equation were determined, where the subscript 2 and 1 refer to non-Newtonian and Newtonian units, respectively. It was found that these parameters were decreased by increasing the degradation time and the energy input. These facts were also explained by the fracture of polymer molecules by mechanical forces. Elctron paramagnetic resonance spectrum of the degraded sample was taken, and it was confirmed that free radicals were produced by the degradation of polystyrene.