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June 13, 2016
Fanny Bardot, LGP2's Ph.D. student, defended her Ph.D. thesis: "Modification of lignins from lignocellulosic pulps in order to incorporate them into ink formulations".
This University Grenoble Alpes doctoral thesis was prepared under the supervision of Gérard Mortha, Professor, and the co-supervision of Anne Blayo, Lecturer-Researcher (Grenoble INP-Pagora / LGP2).
The originality of this work is to use lignin, an aromatic macromolecule from lignocellulosic biomass, in replacement of petroleum-based resins for the formulation of inks for food contact packaging applications.
Different chemical modifications were carried out on commercial lignins, in order to make them compatible with the ink components. Used reagents and processes were chosen in order to limit the environmental impact of the whole value chain. Chemical modifications were monitored by several analytical techniques such as GPC SEC for the molar mass distribution and NMR and FTIR spectrometry for the monitoring of lignin functional groups. Ink properties were characterized by rheological and colorimetric (CIE L*a*b* system) measurements on printed samples.
Among the significant results, changes in hydrophilic/hydrophobic balance were particularly noticed. Furthermore, the colour gamut of modified lignin-based inks was enhanced, compared to the one of unmodified lignin-based inks. Two applications emerged from this work: (1) formulation of lignin-based bio-sourced inks, which meet most of the industrial requirements, and (2), development of a modified lignin-based coating which improved barrier properties of recycled paperboard.