The effect of crystallinity on the rheological behavior of poly(lactide)

Jinlin Wang, Robert Kean, Jed Randall, David Giles

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5 Scopus citations


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 languageEnglish (US)
Pages (from-to)393-405
Number of pages13
JournalInternational Journal of Polymer Analysis and Characterization
Issue number5
StatePublished - 1998

Bibliographical note

Funding Information:
This work was supported by a NIST ATP grant to Cargill Incorporated.


  • Crystallinity
  • Poly(lactide)
  • Rheology
  • Tacticity
  • Thermal degradation


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