This article presents the effect of the addition of condensed tannins, used as a reticulation agent, on the polymerization of furfuryl alcohol during wood furfurylation, as well as the effect of these condensed tannins on the thermal stability of modified wood. Three kinds of dicarboxylic acids (adipic acid, succinic acid, and tartaric acid), as well as glyoxal, used as model of a wood reticulation agent, were used to catalyze the polymerization of furfuryl alcohol or tannin-furfuryl alcohol solutions. Impregnation of furfuryl alcohol or tannin-furfuryl alcohol solution into the wood, followed by curing at 103 °C for a specific duration, was performed for the wood modification. The thermal stability of the obtained tannin-furfuryl alcohol polymers and their corresponding modified woods was investigated. The leaching resistance and dimensional stability of the modified woods were also evaluated. Results indicated that the partial substitution of furfuryl alcohol by the tannins improved the polymerization reactivity in conditions where furfuryl alcohol alone did not lead to the formation of a solid polymeric material. The thermal stability and leaching resistance of the furfurylated wood in the presence of tannins were improved. Dimensional stability was also improved for furfurylated samples, but the effect of tannin addition was not so obvious, depending on the acidic catalyst used.

Wood has been investigated for bioplastic production because of its abundance and biorenewability to reduce dependence on petro-based plastics. A series of experiments have been carried out to graft myristic acid, chosen as the fatty acid model, onto spruce sawdust using trifluoroacetic anhydride (TFAA) as the impelling agent without any solvent. The reaction was performed rapidly, leading to high ester content. Most of the hydroxyl groups in wood structure reacted with myristic acid, as demonstrated by FTIR and CPMAS ¹³C NMR. XRD measurements indicated a decrease in wood crystallinity. Myristic acid-esterified wood showed higher thermal stability by TGA and DSC and delivered several softening temperatures, as observed by TMA. Thermoplastic and translucent films were obtained after pressing at a high temperature. Scanning electron micrographs revealed that pressed esterified wood at the high temperature showed complete disappearance of fibrous structure to a smooth and homogenous surface, indicating that thermal fluidity was achieved during pressing. Esterified sawdust film also showed surface hydrophobicity by contact angle measurements.

Fatty acids (FA) and their derivatives with long alkyl chain structures are good candidates for wood esterification to confer thermoplastic properties to wood. Nevertheless, they do not react easily with hydroxyl groups of wood. In this study, we investigated the reactivity of wood with various fatty acids of different chain lengths using trifluoroacetic anhydride (TFAA) as the impelling agent in various reaction conditions. Generally, the esterification of fatty acids without solvents resulted in higher Weight Percentage Gain (WPG) and ester content than the reaction in the presence of CH₂Cl₂. The esterification reaction could be performed effectively at room temperature, though an increased reaction temperature provoked degradation of the esterified wood. WPG of 67% was obtained for the C3 and 253% for the C16 alkyl chain analogs, respectively. Nevertheless, the ester content was fairly uniform, with values between 10.60 and 11.81 mmol ester/gram of wood for all chain lengths. A higher quantity of reagent led to higher ester content, which tended to stabilize after a ratio of 1:4 wood and TFAA/FA. The esterification reaction was performed rapidly, with an ester content between 7.65 and 9.94 mmol ester/gram of wood being achieved only after 15 min of reaction. Fourier transform infrared spectroscopy (FTIR) analysis was performed to confirm the drastic chemical changes of wood before and after esterification. Morphological observation by scanning electron microscope (SEM), softening measurement by thermomechanical analysis (TMA), and contact angle measurements demonstrated the possibility of esterified spruce wood being applied as a new bioplastic.

To address the environmental impact of petroleum-derived plastics, lignocellulose esters provide a promising renewable alternative. However, research has primarily focused on linear cellulose esters, leaving raw biomass aromatic derivatives largely overlooked. Herein, we report a one-pot, room-temperature synthesis of cinnamate and benzoate esters from microcrystalline cellulose (MCC) and raw pine sawdust. A breakthrough finding reveals that pine esters consistently outperform pure MCC, achieving tensile strengths of 5–8 MPa (vs. 1–3 MPa for MCC) possibly due to a lignin-driven synergistic effect facilitating π–π stacking. The resulting films are hydrophobic (contact angles 80–100°) and fully thermoplastic. Cinnamates emerge as a technically superior and “greener” alternative to benzoates, paving the way for the direct upcycling of wood waste into sustainable packaging materials within a circular economy.

Bio-based thermoplastic film from flax fiber and fatty acid (FA) was obtained using trifluoroacetic anhydride (TFAA) as an impelling agent. Different quantities of TFAA/FA, size of flax fiber, and fatty acids were applied to investigate chemical structure in relation to the mechanical properties. Decreasing the quantity of TFAA/FA by almost half from 1:4 to 1:2.5 (flax to TFAA/FA) only reduces by 22% the weight percent gain (WPG) and ester content and reducing flax fiber size slightly increases the WPG and ester content. All the treatments showed significant chemical structure modification, observed by FTIR and solid CP/MAS 13C NMR, confirming the presence of carbonyl ester groups and alkyl chains, in relatively similar intensities. The crystallinity index (CrI) of esterified flax was evaluated by comparing the signal of solid CP/MAS 13C NMR in crystalline and amorphous regions and CrI was higher in esterified flax using a lower quantity of reagent and longer fatty acid. Esterified flax in a high quantity of reagent showed ductile or flexible behavior. Decreasing the reagent to 1:2.5 significantly increases the tensile strength and Young’s modulus, and decreases the elongation at break, presenting more brittle and stiff material. Using flax fiber in the original size results in slightly higher tensile strength and Young’s modulus and slightly lower elongation than milled flax. The tensile strength and Young’s modulus of stearic acid esterified flax obtained in this research were higher than myristic acid and comparable to the polyethylene plastics-LDPE and HDPE.