Metal–phenolic network (MPN) foams are prepared using colloidal suspensions of tannin‐containing cellulose nanofibers (CNFs) that are ice‐templated and thawed in ethanolic media in the presence of metal nitrates. The MPN facilitates the formation of solid foams by air drying, given the strength and self‐supporting nature of the obtained tannin–cellulose nanohybrid structures. The porous characteristics and (dry and wet) compression strength of the foams are rationalized by the development of secondary, cohesive metal‐phenolic layers combined with a hydrogen bonding network involving the CNF. The shrinkage of the MPN foams is as low as 6% for samples prepared with 2.5–10% tannic acid (or condensed tannin at 2.5%) with respect to CNF content. The strength of the MPN foams reaches a maximum at 10% tannic acid (using Fe^(III) ions), equivalent to a compressive strength 70% higher than that produced with tannin‐free CNF foams. Overall, a straightforward framework is introduced to synthesize MPN foams whose physical and mechanical properties are tailored by the presence of tannins as well as the metal ion species that enable the metal–phenolic networking. Depending on the metal ion, the foams are amenable to modification according to the desired application.

This study presents the preparation of polypropylene composites filled with mixtures of household waste of mate-tea and eucalypt particles and aims to increase the economic value chain of mate-tea. Filler mix- tures in proportions ranging from 0% to 60% with a fixed PP matrix at 40% were prepared in order to eval- uate only the effect of the filler on thermochemical, physical and mechanical properties and on the morphology. The main findings showed that the addition of filler from natural sources decreased thermal stability of composites, but that the temperature of crystallisation increased. Composites with a higher proportion of wood particles showed higher hydrophobic character; however, only the composites with 60% and 54% of mate-tea waste particles showed significantly higher results for water absorption. The use of eucalypt particles increased more mechanical properties than that of household waste, which proves its efficiency as filler. Nevertheless, the use of household waste also increased the properties of the final product and showed that it can be a good alternative for the use of renewable materials in the production of polymeric composites.201

The forest sector plays an important role in the circular bioeconomy due to its focus on renewable materials that can substitute fossil or greenhouse gas emissions-intensive materials, store carbon in bio-based products and provide ecosystem services. This study investigates the state of the bioeconomy in Brazil and its forest industry. Specifically, this study presents some examples of novel wood-based products being developed or manufactured in Brazil and discusses possible opportunities for the development of the country’s forest sector. The pulp and paper industry plays an important role in the forest sector. It has also been showing advancements in the development of cascading uses of wood invalue-added products, such as nanocrystalline cellulose, wood-based textile fibers, lignin-based products, and chemical derivatives from tall oil. Product and business diversification through the integration of the pulp and paper industry to biorefineries could provide new opportunities. Moreover, biochemicals derived from non-wood forest products, such as resin and tannins could promote diversification and competitiveness of the Brazilian forest industry. Although some engineered wood products are still a novelty in Brazil, the market for such products will likely expand in the future following the global trends in wood construction.

We report on the combination of cellulose nanofibrils (CNF) and condensed tannins from Acacia mearnsii for the development of hybrid, functional films. The tannins are fractionated and concentrated in polyphenolics that are used to functional components in the hybrid materials. Co-grinding of wood fibers with the tannins in aqueous media allows simultaneous fiber deconstruction and in situ binding of tannins on the freshly exposed cellulosic surfaces. Hence, a tightly-bound bicomponent system is produced, which is otherwise not possible if typical adsorption protocols are followed, mainly due to the extensive hydration typical of CNF. A nonionic surfactant is used to tailor the cellulose-tannin interactions. The proposed strategy not only enables the incorporation of tannins with CNF but endows a high and prolonged antioxidant effect of films formed by filtration. Compared to tannin-free films, those carrying tannins have a considerable higher tensile strength and absorb less water. In addition, they show selective absorption of ultraviolet light while maintaining optical transparency in the visible range. The proposed simple protocol for incorporating tannins and surfactants with CNF, is suitable to produce functional materials. This is possible by understanding associated interfacial phenomena in the context of sustainable materials within the concept of the circular bioeconomy.