Abstract:

Objective: Directional recombinant technology was used to prepare Cupressus funebris scrimber, the structure and performance were analyzed, so as to reveal the internal causes of the performance changes of cypress wood after it is prepared into scrimber, and provide technical references and theoretical basis for the high-value utilization of cypress wood in plantation forests. Method: Different compression rates (80%, 100%, and 120%) were adopted to prepare C. funebris scrimbers, and subsequently the effect of preparation process and compression rates on the water resistance and mechanical properties (bending properties and horizontal shear properties) of C. funebris scrimbers were investigated. Ultra-deep field microscopy (UDM), cold field emission scanning electron microscopy (SEM), laser confocal microscopy (LSM), and transmission electron microscopy (TEM) were used to observe the microstructural changes and glue distribution of scrimber. Also, the vertical profile density of scrimber was studied by profile densitometry. Result: As the compression rates of scrimber increased, the surface color deepened, the profile density more uniform, the water absorption rate (WAR), thickness swelling rate (TSA), and width swelling rate (WSA) gradually decreased, and the modulus of rupture (MOR) and horizontal shear strength (HSS_⊥) gradually increased. The WAR of scrimber was the lowest at a compression rate of 120%, which was 34.73% lower than that of C. funebris. The maximum MOR and HSS_⊥ were 125.77 and 17.05 MPa, respectively, which were 53.47% and 84.32% higher than those of C. funebris. The result of profile density, SEM, LSM, and TEM showed that the improvement of water resistance and mechanical properties of the scrimber was mainly due to the compression denseness of wood cells, the wider distribution of glue, in addition, gluing sites formed by the phenol-formaldehyde resin (PF) among more cells enhanced connections of cell lumen and middle lamella, thus reducing the water entering channels during water absorption, inhibiting the rebound of cell cavities and strengthening the weak structure of middle lamella. Conclusion: The C. funebris can be prepared into scrimber with significantly improved mechanical properties by directional recombination technology, in which water resistance increased with the increase of compression rates. The performance reached the best when the compression rate was 120%.

Key words: reconstituted material, Cupressus funebris scrimber, compression rates, water resistance, bending properties, horizontal shear performance