Construction of superhydrophobic woods with high abrasion resistance is still a major challenge, and micro analysis for abrasion resistance is scarce. To improve these issues, cellulose nanocrystals (CNC)@SiO₂@phosphorylated lignin (PL) rods were prepared by SiO₂ in situ generated on CNC, and then the modified lignin attached to the CNC@SiO₂ rods surface. Subsequently, the superhydrophobic coating was constructed using hydrophobic modified CNC@SiO₂@PL rods as the main structural substance by simple spraying or rolling them onto wood surfaces, and both polydimethylsiloxane (PDMS) and epoxy resin were used as the adhesives. The resulting coating had excellent superhydrophobic properties with a water contact angle (WCA) of 157.4° and a slide angle (SA) of 6°. The introduced PL could enhance ultraviolet (UV) resistance of the coating due to the presence of these groups that absorbed UV light in lignin. In the abrasion resistance test, compared with the SiO₂/PL coating, the abrasion resistance of the one with CNC was much higher, suggesting that CNC could improve the abrasion resistance of the coating due to its high crystallinity and excellent mechanical strength. The coating with PDMS performed better than the one with epoxy resin because the soft surface could offset part of the external impact by deformation in the abrasion process. This was also consistent with the results of the nanoindentation (NI) tests. In view of the simple preparation and good performance, this superhydrophobic wood will have broad application potential.

UV irradiation leads to various usage issues of engineered wood products (EWPs), including discoloration and declined mechanical performance. The radical generation and physico-chemical changes of the wood-phenol formaldehyde (PF) adhesive interphase during alternating UV irradiation were investigated in this paper, aiming to understand the oxidation and degradation of EWPs in daily applications. Electron spin resonance spectroscopy demonstrated that UV irradiation activates the phenol ring in lignin and PF adhesive, generating the reactive oxygen species (ROSs) composed of phenoxyl radicals, singlet oxygen, superoxide anion, and hydroxyl radicals. Experiments also showed that ROSs cleavage the weak covalent bonds in the cell wall and PF adhesive, triggering photon-oxidation and degradation. The cavities in the UV irradiated cell wall were observed after UV irradiation by scanning electron microscopy. Nanoindentation analysis also demonstrated the reduced mechanical performance of cell walls in the wood-adhesive interphase and bulk wood, leading to the significant reduction in the shearing and compression strength of wood-PF adhesive bonds. In contrast, the chemical structure and mechanical performance of PF adhesive remained after UV irradiation, suggesting better stability to UV exposure. It has been demonstrated that the degradation of wood has priority during the alternating UV irradiation.

Timber architectures have arisen as sustainable solutions for high-rise and long-span buildings, assisting in implementing a circular economy. The creep strain dissipation of laminated veneer lumber (LVL) was investigated in this work to understand the inherent creep behaviors of LVL derived from natural wood. The results demonstrated a significant loading regime dependency of the creep behaviors of LVL. Coupled creep strain dissipation that transits/is parallel to the wood–adhesive interface was proven in the creep deformation of flat-wise and edge-wise bent LVL. In contrast, the creep strain dissipated considerably along the wood–adhesive interface when the LVL was subjected to axial compression creep. Further investigation into the morphologies of LVL after creep revealed that direct contact between the loading plane and wood–adhesive interface could be a plausible trigger for the accelerated deformation and the resultant plastic deformation of the LVL after creep. We believe that this work provides essential insights into the creep strain dissipation of LVL. It is thus beneficial for improving creep resistance and assisting in the long-term safe application of LVL-based engineered wood products in timber architectures.