Local demixion in plasticized polylactide probed by electron spin resonance

•ESR technique to assess microphase separation or heterogeneities in plasticized PLA.•Probing the chain mobility and microphase separation along the film thickness.•Equivalence time/spatial scales in diffusion phenomena to get spatial resolution.•Reconstruction of temperature profile along the PLA f...

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Bibliographic Details
Published in:Journal of magnetic resonance (1997) 2013-08, Vol.233, p.37-48
Main Authors: Courgneau, Cécile, Vitrac, Olivier, Ducruet, Violette, Riquet, Anne-Marie
Format: Article
Language:English
Subjects:
Agricultural sciences
Citrates - chemistry
Crystallization
Diffusion
Electron paramagnetic resonance
Electron Spin Resonance Spectroscopy - methods
Film thickness
Glycols
Life Sciences
Magnetic resonance
Microphase separation
Plasticizers
Plastics
Polyesters - chemistry
Polyethylene Glycols
Polylactides
Risk
Separation
Spin-probe ESR
Temperature
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Summary:•ESR technique to assess microphase separation or heterogeneities in plasticized PLA.•Probing the chain mobility and microphase separation along the film thickness.•Equivalence time/spatial scales in diffusion phenomena to get spatial resolution.•Reconstruction of temperature profile along the PLA film thickness.•Measured excess temperatures related to local shifts in the Tg along the film thickness. Improving the barrier properties to gas and organic compounds of biosourced polyesters, such as polylactides (PLAs), by increasing their crystallinity has been suggested by several authors. This paper investigates the risk of microphase separation for a technological approach that would involve a plasticization of PLA, to further its crystallization kinetics, with common plasticizers: Acetyl tributyl citrate (ATBC) and Poly(ethylene glycol) (PEG). Overplasticization effects following microphase separation were monitored along the film thickness by exposing dynamically thermo-compressed films to nitroxide spin-probes. The method enabled a scan of the local polymer mobility for different concentration profiles in spin-probes, with in particular a maximum moving continuously in time towards the geometric center. The results were interpreted as excess local temperatures that would give similar ESR spectra motion in the bulk. It was shown that measured excess temperatures could be related to local shifts in the glass transition temperature along the film thickness.
ISSN:1090-7807
1096-0856
DOI:10.1016/j.jmr.2013.04.006