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Theses

Modification des propriétés de surface de matériaux lignifiés : impact d'un greffage par voie physique

Abstract : In a context of green chemistry, this thesis deals with the surface properties of lignified materials, with a focus on the impact of physical grafting treatments. The objectives were 1) to confer hydrophobic properties to the surface of thermoplastic starch films, 2) to control the grafting / scission reactions within starch-lignin systems upon irradiation, 3) to elucidate the contribution of topography and chemical structure to the wetting phenomenon. An industrial grass alkali lignin recovered from the pulp and paper industry was incorporated into a starch-glycerol matrix at a 20% rate, using either potato or wheat starch. Thermoplastic sheets were obtained by extrusion, showing distinct properties as a function of starch origin, wheat starch properties being more dependent on the formulation and extrusion conditions. The sheets were submitted to electron beam irradiation at 200 and 350 kGy, before and after compression-moulding. Both compression-moulding and irradiation leads to a decrease of surface wettability with final contact angles characteristic of hydrophobic properties. The effect is more pronounced with irradiation and increases with irradiation dose. It is however not correlated to roughness variations, as shown by MEB and AFM observations. An investigation of the reactivity of the phenolic compounds during the treatments was undertaken. Extractible p-coumaric and ferulic acids undergo an up to 60 % conversion due to an irradiation-grafting process, whereas extrusion has little effect on them. In the presence of these compounds lignin condensation reactions prevail over depolymerisation.
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https://pastel.archives-ouvertes.fr/pastel-00605664
Contributor : Dan Zheng <>
Submitted on : Sunday, July 3, 2011 - 6:03:48 PM
Last modification on : Monday, October 19, 2020 - 11:04:38 AM
Long-term archiving on: : Tuesday, October 4, 2011 - 2:21:43 AM

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  • HAL Id : pastel-00605664, version 1
  • PRODINRA : 246134

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Citation

Dan Zheng. Modification des propriétés de surface de matériaux lignifiés : impact d'un greffage par voie physique. Polymères. AgroParisTech, 2011. Français. ⟨NNT : 2011AGPT0006⟩. ⟨pastel-00605664⟩

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