The reaction of citric acid with wood veneers was studied by Cross Polarization Magic Angle Spinning Nuclear Magnetic Resonance (CP MAS ¹³C NMR) and matrix assisted laser desorption ionization time of flight (MALDI ToF) mass spectrometry. The analysis showed that reactions of citric acid occurred with both lignin and carbohydrate constituents of wood. The reactions occurring are esterifications between the carboxylic acid functions of citric acid and the numerous aromatic and aliphatic hydroxyl groups of the main wood constituents. Reaction of citric acid with glucose as a simple model compound of carbohydrates hydroxyl groups also yielded reactions leading to linear and branched oligomers by esterification. The result indicate that the reactions of esterification are accompanied in parallel by some internal rearrangements of lignin. The applied results on bonding wide flat wood surfaces such as veneers to obtain LVL panels yielded excellent strength results even if the conditions of pressing were more drastic than what is usual for this application. The applied bonding results have shown that citric acid has great potential to be used as a bio-binder for wood veneers.

This study investigated the effects of different treatments of coir fibers (Cocos nucifera L.), and cement:coir ratio on physical and mechanical properties of cement-bonded composites. Three treatments: adding 4% of CaCl2, immersion in hot water at 80°C for 90 minutes, and immersion in NaOH aqueous solution at 5% for 72 hours and two cement:fiber ratios (3:1 and 4:1) were chosen for manufacturing 24 panels. After 28 days of setting, characterization was made through static bending (MOE, MOR), parallel compression (COMP), internal bonding (IB), thickness swelling (TS), and water absorption (WA) (2 and 24 hours of water immersion) tests. Treating coir fibers with hot water provided an improvement in the panel’s properties. This treatment had better results in MOE and COMP. Panels produced with CaCl2 addition were resistant as well; however coir fibers treated with NaOH produced cement/coir composites with unsatisfactory physical and mechanical properties.

The objectives of the present work were to evaluate the chemical compatibility between coir (Cocos nuciferaL.) and cement and to study treatment methods to improve this compatibility. In the inhibition test, cement hydration temperature evolution was measured in the absence and presence of untreated and treated coir fibres (cold water, hot water and NaOH), besides the addition of 4% of CaCl₂. The chemical characterization of untreated and treated coir fibres was done by determining the content of extractives, lignin, and holocellulose. The inhibition test graded the untreated fibre as “extreme inhibition,” ratifying the need to provide it a treatment. Treatments done on coir fibres affected positively the compatibility between cement and fibre, reducing the inhibition. The treatments reduced the lignin coir fibres’ and extractives proportion, whose variation was significantly correlated with the reduction of the inhibitory index. These results indicate a possibility for future incorporation of these fibres into the production of mineral composites.