Preparation and characterization of linear and star-shaped poly L-lactide blends

ABSTRACT A series of star‐shaped poly(l‐lactide) (sPLLA) with different branch length was synthesized by ring‐opening polymerization of l‐lactide using pentaerythritol as initiator and stannous‐octoate as catalyst. The structures and properties of the sPLLAs were characterized by 1H‐NMR, rheology, d...

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Bibliographic Details
Published in:Journal of applied polymer science 2016-01, Vol.133 (2), p.np-n/a
Main Authors: Khajeheian, Mohammad B., Rosling, Ari
Format: Article
Language:English
Subjects:
biopolymers and renewable polymers
Blends
Crystallization
extrusion
Materials science
Melts
Molecular structure
Polymer blends
Polymerization
Polymers
rheology
Shear viscosity
Thermal properties
viscosity and viscoelasticity
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Summary:ABSTRACT A series of star‐shaped poly(l‐lactide) (sPLLA) with different branch length was synthesized by ring‐opening polymerization of l‐lactide using pentaerythritol as initiator and stannous‐octoate as catalyst. The structures and properties of the sPLLAs were characterized by 1H‐NMR, rheology, differential scanning calorimetry, and size‐exclusion chromatography. The star‐shaped polymers were blended with a linear PLLA resin (3051D; NatureWorks) and studied for their melt flow and thermal properties. Blends containing 10 wt % of sPLLA displayed equivalent zero shear viscosities to PLLA 3051D, however displaying stronger shear thinning and increased melt elasticity. The blends exhibited also similar thermal and crystallization properties as the PLLA 3051D. A higher ratio of low molecular weight sPLLA (30 wt %; Mwtotal: 2500 and 15,000 g mol−1) lowered the zero viscosity and increased shear thinning of PLLA 3051D. Crystallization of PLLA 3051D appears to increase at 30 wt % blends with the higher molecular weight sPLLA, while the star‐shaped structure acts as a nucleating agent. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42231.
ISSN:0021-8995
1097-4628
DOI:10.1002/app.42231