The production of chemicals via acid-catalysed dehydration of sugars is inevitably related to the formation of co-products. Noteworthy, a black and viscous polymeric co-product called humins can be formed in significant quantities. Humins are heterogeneous and polydisperse macromolecules, mainly constituted by furanic rings and aldehydes, ketones and hydroxyls as main functional groups. For many years, scientists focused on finding a way to avoid humins formation during biorefinery processes but that appears to be almost inevitable. In current biorefinery process designs, humins are burnt to generate heat that can be integrated back into the process. However, the attention is now shifting towards ways to make high value-added products from humins, to further improve the process economics of biorefineries. An extensive analysis of the structure and pysico-chemical properties of humins was performed to support humins application research. Particular attention was paid to the identification of transitions and chemical reactions occurring in humins, by using advanced thermoanalytical techniques. It was demonstrated that it is possible to obtain a thermoset polymer with different properties, based on the treatment used. The cross-linking behaviour was then further elucidated by studying optimal initiators and through a deep investigation on the kinetics of cross-linking. Humin based thermosets were tested for different applications. The potential of all-humins-matrix in combination with natural fibres was investigated. Good interaction between organic matrix and natural fibres was observed, making humins very promising for the next generation of biobased thermoset materials. The use of humins as matrix is a sustainable solution to develop all “green” composites, with high hydrophobic properties and mechanical properties comparable with other biobased thermosets used in several commercial applications. Considering the very good affinity with lignocellulosic materials, a new process option was evaluated for fibre modification to enhance the interaction at the interface between cellulosic fibres and common polymeric matrices such as polypropylene. This study also allowed to get insights into the interactions between cellulose and humins. To further exploit these type of applications, wood modification with humin resin was studied. Dimension and weight stability of the modified wood after immersion in water confirmed improved hydrophobicity of the final material. Mechanical properties were studied by DMA. This study demonstrates that this new impregnation technique can improve the dimensional stability of wood, without compromising on the mechanical properties by valorising humins. Finally, the possibility to use humins as a binder to enhance bitumen’s rheological properties and decrease its environmental impact was investigated.

La production de molĂ©cules plateformes via la dĂ©shydratation des sucres catalysĂ©e par un acide est inĂ©vitablement liĂ©e Ă  la formation de sous-produits. Notamment, un sous-produit appelĂ© humine peut ĂŞtre formĂ© en quantitĂ©s importantes. Les humines sont des macromolĂ©cules hĂ©tĂ©rogènes et polydisperses, constituĂ©es principalement de composĂ©s furaniques. Pendant nombreuses annĂ©es, les scientifiques ont cherchĂ© Ă  trouver un moyen d’Ă©viter la formation d’humines au cours des processus de bioraffinage, mais cela semble presque inĂ©vitable. Les recherches actuelles se concentrent aujourd’hui sur les moyens de fabriquer des produits Ă  haute valeur ajoutĂ©e Ă  partir d’humines, afin d’amĂ©liorer la rentabilitĂ© des bioraffineries. Une analyse approfondie de la structure et des propriĂ©tĂ©s physico-chimiques des humines a Ă©tĂ© rĂ©alisĂ©e dans ce travail de thèse afin de dĂ©velopper de nouveaux axes de recherche sur les applications potentielles des humines, en particulier l’identification des transitions et des rĂ©actions chimiques se produisant dans les humines, en utilisant des techniques thermo-analytiques avancĂ©es. Il a Ă©tĂ© dĂ©montrĂ© qu’il est possible d’obtenir un polymère thermodurcissable avec diffĂ©rentes propriĂ©tĂ©s, en fonction du traitement utilisĂ©. Les thermodurcissables Ă  base d’humine ont Ă©tĂ© testĂ©s pour diffĂ©rentes applications. Le potentiel des humines comme matrice en combinaison avec des fibres naturelles afin de rĂ©aliser des composites 100 \% biosourcĂ©s a Ă©tĂ© Ă©tudiĂ©. Une bonne interaction entre la matrice organique et les fibres naturelles a Ă©tĂ© observĂ©e, rendant les humines très prometteuses pour la prochaine gĂ©nĂ©ration de matĂ©riaux et de composites thermodurcissables biosourcĂ©s. L’utilisation d’humines comme matrice est une solution durable pour dĂ©velopper des composites “verts”, avec des propriĂ©tĂ©s hydrophobes et mĂ©caniques Ă©levĂ©es. Compte tenu de la très bonne affinitĂ© avec les matĂ©riaux lignocellulosiques, de nouvelles voies ont Ă©tĂ© proposĂ©es pour la modification des fibres afin de renforcer l’interaction entre les fibres cellulosiques et certaines matrices polymĂ©riques, telles que le polypropylène par exemple. Cette Ă©tude a Ă©galement permis de mieux comprendre les interactions entre la cellulose et les humines. Pour exploiter ce type d’applications, la modification du bois avec des humines a Ă©tĂ© Ă©tudiĂ©e. La stabilitĂ© dans l’eau du bois modifiĂ© a confirmĂ© l’amĂ©lioration de l’hydrophobicitĂ© du matĂ©riau final. Cette Ă©tude montre que cette nouvelle technique d’imprĂ©gnation peut amĂ©liorer la stabilitĂ© dimensionnelle du bois sans compromettre les propriĂ©tĂ©s mĂ©caniques tout en valorisant les humines. Enfin, la possibilitĂ© d’utiliser des humines comme liant pour amĂ©liorer les propriĂ©tĂ©s rhĂ©ologiques du bitume et rĂ©duire son impact sur l’environnement a Ă©tĂ© Ă©tudiĂ©e.