Three different formulations of bio-based polyurethane (PU), varying the weight ratio between Organosolv lignin and a commercial isocyanate, were synthesized. The coating formulations were characterized by SEM, pyrolysis-GC/MS, FTIR spectroscopy and FTIR mapping, which confirmed the successful formation of urethane bonds between commercial isocyanate and hydroxyl groups deriving from lignin. The coatings were applied on beech wood samples to measure color and contact angles, and eventually FTIR mapping of the coated wood samples was performed. FTIR mapping is an interesting tool to monitor the distribution of PU chemical bonds on the coating surface and to evaluate the homogeneity of the applied coating films. Increasing the lignin content of the PU coatings results in more red-yellow and darker tones, while the commercial PU coating is transparent. For a higher lignin concentration, the solid content as well as the weight gain of the applied coatings increase. A higher percentage of lignin in the prepared PU formulations leads to superficial cracks and therefore higher coating permeability compared to the commercial PU, but the prepared lignin-based PU coating still makes a raw wood surface significantly more hydrophobic. Apparently, additives such as film-formers with low surface tension to counteract cracks’ formation are necessary to improve the performance of lignin-based PU coatings.

Wood coatings prolong the service life of wood-based products, but they are usually of synthetic origin. The aim of the present article is to reduce the fossil-based compounds in a commercial waterborne acrylic coating by CNC addition and to test its performance. The coatings were applied on European beech and Norway spruce wood in order to test durability against Gloeophyllum trabeum (brown wood rot) and Trametes versicolor (white wood rot). Artificial weathering and blue stain, contact angle, physical tests (adhesion, impact and scratch test), chemical (FTIR) and morpho-anatomical analysis (SEM) were carried out. CNC addition increased viscosity, limiting the spreading of the coating into wood pores as visible after SEM observation, which reduced coating adhesion on the substrate. CNC improved fungal resistance as seen by a reduced mass loss and FTIR spectroscopy thanks to crosslinks formation, which reduced water sorption as well. Color change was not significant, and, on the other hand, glossiness was reduced but resulted as more homogeneous than control. CNC addition gave good results also in blue stain protection. CNC improved scratch resistance, but no visible change to impact was registered. CNC has promising results in coatings depending on wood and fungal species and presence of further commercial additives (biocides).

Biorefineries are an important pillar to conduct the transition toward a circular bioeconomy. Forestry value chains produce wood biomass from harvesting and processing residues that have potential to be used in biorefineries, but currently, these residues are mostly used for energy generation. New biorefineries and new methodologies of wood fractionation allow the production of high value-added products based on carbohydrates and lignin. However, biorefineries based on lignocellulosic feedstock are still few in European countries and even less in Italy. The present study analyses the processes involved in a scenario of establishment of forest biorefineries, reviewing the main components and the actual organization of forestry value chains in Italy. The aim is to have a general vision, to identify and to focus the possibilities of the actual value chains and to fill gaps. The development of the territories is thought of in a perspective of a broader repertoire and more branched value chains than simple energy-generation end use, reviewing the tool for a feasibility study that could potentially involve lignocellulosic biorefineries also based on forest-wood industry feedstocks.

The sudden availability of Italian stone pine (Pinus pinea L.) wood due to the infestation of pathogenic fungi and insects highlighted the need to promote its use as a short supply chain resource in Italy and other Mediterranean countries. However, the durability of stone pine sapwood must be enhanced if outdoor use is to be considered. The impregnability of stone pine wood was studied following the standard EN 351-1:2008, using immersion, vacuum, and high-pressure methods with natural waxes and organic solvent-based and copper-amino-based preservative solutions. The efficacy of the impregnation was determined by calculating the kilos of preservative absorbed per cubic meter of wood and by measuring the penetration depth of the preservative. Thermal modifications were carried out using five different maximum temperatures, and their efficacy was determined by measuring the mass loss and color change. Subsequent to thermal treatments, the wood was exposed to a water-vapor-saturated atmosphere, and the increase in mass was calculated for different periods. Stone pine and Scots pine sapwoods showed similar response to the treatments with the exception of soaking impregnation methods where stone pine showed higher uptake, in particular when Silvanolin was used. Our investigation shows that stone pine can be a suitable short supply chain resource in Italy that, when impregnated, could be tested for outdoor use, exactly as is the case with Scots pine.

Lignin-based polyurethanes represent a promising strategy for developing more sustainable wood coatings by partially replacing fossil-derived polyols with renewable aromatic biopolymers. In this study, a polyurethane formulated with organosolv lignin (LPU) was synthesized and applied on two non-durable European wood species, Fagus sylvatica L. and Picea abies L., and compared with a commercial fossil-based polyurethane (CPU). Coated samples were evaluated for color stability, gloss evolution, wettability, adhesion, impact and scratch resistance, and biological durability. Accelerated ageing was performed under xenon-light irradiation, while decay resistance was assessed against Gloeophyllum trabeum and Trametes versicolor. Additional tests examined susceptibility to blue-stain fungi and surface morphology via SEM. LPU produced a matte film with intrinsically darker coloration but excellent chromatic stability and minimal gloss variation during ageing. Its initial hydrophobicity was higher on beech and comparable to CPU on spruce. Although CPU exhibited superior adhesion and slightly better mechanical resistance, LPU provided enhanced protection against blue-stain fungi—particularly on spruce—and a more uniform response to decay fungi across wood species. Overall, despite its darker appearance, the lignin-based formulation offered functional protection comparable to the commercial coating, confirming its potential as a viable bio-based alternative for above-ground wood applications.