Viscoelastic Properties of Poly(L-lactic acid)

Abstract

The dynamic viscoelastic properties of poly(L-lactic acid) (PLLA) were investigated in the molten state. The time-temperature superposition principle can be utilized and the master curves were obtained. The temperature dependence of the shift factor was expressed by the WLF equation. The fractional free volume at the glass transition temperature, the temperature coefficient of the fractional free volume, and the Vogel temperature were determined. These values are smaller than those of poly(methyl methacrylate) and polystyrene. Moreover the characteristic parameters; zero-shear viscosity, steady-state compliance, and elasticity coefficient were evaluated at 180 °C as a reference temperature.