The theological behavior of poly(lactide) samples, with different levels of crystallinity, was investigated. The dynamic shear storage and loss modulus were obtained as a function of temperature at 1 rad/s. From the glassy to the rubbery region, the dynamic shear modulus decreased more than two decades for the initially amorphous poly(lactide) (containing 1% of D-lactide) and about one decade for the annealed (semicrystalline) sample. The dynamic shear modulus data showed that the crystallization rate increased with a decrease of D-lactide in poly(lactide) and an increase of talc (a nucleating agent) in the sample. The steady-state and dynamic shear viscosity were measured at 210°C. The results indicated that the Cox-Merz rule can be used to relate the dynamic shear viscosity to the steady-state shear viscosity. A master curve for the amorphous poly(lactide) was obtained, using the time-temperature superposition principle. The result showed that the temperature dependence of the shift factor can be described by the Arrhenius equation below the glass-transition region, and the WLF (Williams-Landel-Ferry) equation above the glass-transition region.
|Original language||English (US)|
|Number of pages||13|
|Journal||International Journal of Polymer Analysis and Characterization|
|State||Published - 1998|
Bibliographical noteFunding Information:
This work was supported by a NIST ATP grant to Cargill Incorporated.
- Thermal degradation