Rheological properties of poly(lactides). Effect of molecular weight and temperature on the viscoelasticity of poly(l-lactic acid)

Cooper-White, Justin J. and Mackay, Michael E. (1999) Rheological properties of poly(lactides). Effect of molecular weight and temperature on the viscoelasticity of poly(l-lactic acid). Journal of polymer science. Part B, Polymer physics, 37 15: 1803-1814. doi:10.1002/(SICI)1099-0488(19990801)37:15<1803::AID-POLB5>3.0.CO;2-M


Author Cooper-White, Justin J.
Mackay, Michael E.
Title Rheological properties of poly(lactides). Effect of molecular weight and temperature on the viscoelasticity of poly(l-lactic acid)
Journal name Journal of polymer science. Part B, Polymer physics
ISSN 0887-6266
0098-1273
Publication date 1999-08-01
Sub-type Article (original research)
DOI 10.1002/(SICI)1099-0488(19990801)37:15<1803::AID-POLB5>3.0.CO;2-M
Open Access Status Not yet assessed
Volume 37
Issue 15
Start page 1803
End page 1814
Total pages 12
Place of publication Easton, PA.
Publisher Wiley
Language eng
Subject 091599 Interdisciplinary Engineering not elsewhere classified
Abstract The dynamic viscoelastic behavior of Poly(l-lactic acid) (PLLA), with molecular weights ranging from 2,000 to 360,000, have been studied over a broad range of reduced frequencies (approximately 1 × 10-3 s-1 to 1 × 103 s-1), using time-temperature superposition principle. Melts are shown to have a critical molecular weight, Mc, of approximately 16,000 g/mol, and an entanglement density of 0.16 mmol/cm3 (at 25°C). PLLA polymers are noted to require substantially larger molecular weights in order to display similar melt viscoelastic behavior, at a given temperature, as that for conventional non-biodegradable polymers such as polystyrene. The reason for this deviation is suspected to be due to steric hindrance, resulting from excessive coil expansion or other tertiary chain interactions. PLLA melts show a dependence of 0 on chain length to the 4.0 power (M[stack 4.0W ]), whilst J[stack 0e ] is independent of MW in the terminal region. Low molecular weight PLLA ( 40,000) shows Newtonian-like behavior at shear rates typical of those achieved during film extrusion. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1803-1814, 1999
Keyword Poly(lactic acid)
Melt viscoelastic behavior
Biodegradable polymer
Terminal region properties
Molecular weight effects
Temperature effects
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Chemical Engineering Publications
 
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