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Title: Coalescence in PLA-PBAT blends under shear flow: Effects of blend preparation and PLA molecular weight

Abstract

Blends containing 75 wt. % of an amorphous polylactide (PLA) with two different molecular weights and 25 wt. % of a poly[(butylene adipate)-co-terephthalate] (PBAT) were prepared using either a Brabender batch mixer or a twin-screw extruder. These compounds were selected because blending PLA with PBAT can overcome various drawbacks of PLA such as its brittleness and processability limitations. In this study, we investigated the effects of varying the molecular weight of the PLA matrix and of two different mixing processes on the blend morphology and, further, on droplet coalescence during shearing. The rheological properties of these blends were investigated and the interfacial properties were analyzed using the Palierne emulsion model. Droplet coalescence was investigated by applying shear flows of 0.05 and 0.20 s{sup −1} at a fixed strain of 60. Subsequently, small amplitude oscillatory shear tests were conducted to investigate changes in the viscoelastic properties. The morphology of the blends was also examined using scanning electron microscope (SEM) micrographs. It was observed that the PBAT droplets were much smaller when twin-screw extrusion was used for the blend preparation. Shearing at 0.05 s{sup −1} induced significant droplet coalescence in all blends, but coalescence and changes in the viscoelastic properties were much more pronounced for themore » PLA-PBAT blend based on a lower molecular weight PLA. The viscoelastic responses were also somehow affected by the thermal degradation of the PLA matrix during the experiments.« less

Authors:
 [1]; ;  [2];  [3];  [4]
  1. Center for High Performance Polymer and Composite Systems (CREPEC), Chemical Engineering Department, Polytechnique Montreal, Montreal, Quebec H3T 1J4, Canada and CREPEC, Department of Chemical Engineering, McGill University, Montreal, Quebec H3A 2B2 (Canada)
  2. Center for High Performance Polymer and Composite Systems (CREPEC), Chemical Engineering Department, Polytechnique Montreal, Montreal, Quebec H3T 1J4 (Canada)
  3. CREPEC, Department of Chemical Engineering, McGill University, Montreal, Quebec H3A 2B2 (Canada)
  4. NatureWorks LLC, 15305 Minnetonka Boulevard, Minnetonka, Minnesota 55345 (United States)
Publication Date:
OSTI Identifier:
22598951
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Rheology; Journal Volume: 60; Journal Issue: 4; Other Information: (c) 2016 The Society of Rheology; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; AMPLITUDES; BRITTLENESS; BUTENES; COALESCENCE; DROPLETS; EMULSIONS; EXTRUSION; MATRICES; MIXING; MOLECULAR WEIGHT; MORPHOLOGY; SCANNING ELECTRON MICROSCOPY; SHEAR; STRAINS; THERMAL DEGRADATION

Citation Formats

Nofar, M., Heuzey, M. C., Carreau, P. J., E-mail: pierre.carreau@polymtl.ca, Kamal, M. R., and Randall, J. Coalescence in PLA-PBAT blends under shear flow: Effects of blend preparation and PLA molecular weight. United States: N. p., 2016. Web. doi:10.1122/1.4953446.
Nofar, M., Heuzey, M. C., Carreau, P. J., E-mail: pierre.carreau@polymtl.ca, Kamal, M. R., & Randall, J. Coalescence in PLA-PBAT blends under shear flow: Effects of blend preparation and PLA molecular weight. United States. doi:10.1122/1.4953446.
Nofar, M., Heuzey, M. C., Carreau, P. J., E-mail: pierre.carreau@polymtl.ca, Kamal, M. R., and Randall, J. Fri . "Coalescence in PLA-PBAT blends under shear flow: Effects of blend preparation and PLA molecular weight". United States. doi:10.1122/1.4953446.
@article{osti_22598951,
title = {Coalescence in PLA-PBAT blends under shear flow: Effects of blend preparation and PLA molecular weight},
author = {Nofar, M. and Heuzey, M. C. and Carreau, P. J., E-mail: pierre.carreau@polymtl.ca and Kamal, M. R. and Randall, J.},
abstractNote = {Blends containing 75 wt. % of an amorphous polylactide (PLA) with two different molecular weights and 25 wt. % of a poly[(butylene adipate)-co-terephthalate] (PBAT) were prepared using either a Brabender batch mixer or a twin-screw extruder. These compounds were selected because blending PLA with PBAT can overcome various drawbacks of PLA such as its brittleness and processability limitations. In this study, we investigated the effects of varying the molecular weight of the PLA matrix and of two different mixing processes on the blend morphology and, further, on droplet coalescence during shearing. The rheological properties of these blends were investigated and the interfacial properties were analyzed using the Palierne emulsion model. Droplet coalescence was investigated by applying shear flows of 0.05 and 0.20 s{sup −1} at a fixed strain of 60. Subsequently, small amplitude oscillatory shear tests were conducted to investigate changes in the viscoelastic properties. The morphology of the blends was also examined using scanning electron microscope (SEM) micrographs. It was observed that the PBAT droplets were much smaller when twin-screw extrusion was used for the blend preparation. Shearing at 0.05 s{sup −1} induced significant droplet coalescence in all blends, but coalescence and changes in the viscoelastic properties were much more pronounced for the PLA-PBAT blend based on a lower molecular weight PLA. The viscoelastic responses were also somehow affected by the thermal degradation of the PLA matrix during the experiments.},
doi = {10.1122/1.4953446},
journal = {Journal of Rheology},
number = 4,
volume = 60,
place = {United States},
year = {Fri Jul 15 00:00:00 EDT 2016},
month = {Fri Jul 15 00:00:00 EDT 2016}
}