Effects of heat-treatment on bonding performance of Betula alnoides

Heat-treatment woods of Betula alnoides were prepared by using vapor as the heat-conducting medium. Effects of heat-treatment time and heat-treatment temperature on equilibrium moisture content, density, pH value, contact angle and bonding performance of Betula alnoides were discussed in this paper. The results indicated that: (1) With the increase of heat-treatment temperature, the equilibrium moisture content, density and pH value of Betula alnoides decreased gradually. (2) With the increase of heat-treatment temperature, the contact angle of Betula alnoides increased from 70.08° to about 100°, resulting in the reduction of bonding strength gradually. Bonding strength of Betula alnoides after heat-treatment was related with the used adhesive. Bonding strength of different adhesives decreased to different extents. The bonding strength of Betula alnoides wood with polyvinyl acetate (PVAC) resin was generally higher than that of melamine-urea-formaldehyde (MUF) resin. The former were 6.35-4.56 MPa, and the latter were 5.60-3.00 MPa. (3) Heat-treatment time influenced equilibrium moisture content, density, contact angle, pH value and bonding strength of Betula alnoides less than heat-treatment temperature. (4) Heat-treatment could affect strength and surface performance of Betula alnoides greatly and the processing medium should be extended.

Study of nano colloidal silica sol based protectant on the prevention of masson pine

In this study, wood protectants were prepared by using manganese chloride, potassium carbonate, borax and nano colloidal silica sol. Effects of the wood protectants on decay resistance, anti-mold property and fire resistance of Pinus massoniana Lamb. were discussed. The results indicated that the optimal formula of the protectant was composed of 20% colloidal silica sol and 8% modifier (manganese chloride + potassium carbonate + borax). Under this formula, the protectant had good permeability and fluidity, accompanied with synergistic effect between colloidal silica sol and modifier. Pinus massoniana Lamb. treated by the protectant with this formula showed good decay resistance, and its mass loss rates after corrosion by Gloeophyllum trabeum and Coriolus versicolor were respectively about 21% and 19%, lower than those of the control group. This indicated that the preferred samples reached I-level decay resistance according to Chinese Forestry Industrial Standards LY/T 1283-2011. Moreover, Pinus massoniana Lamb. under this formula had good anti-mold property, manifested by 100% resistance to Aspergillus niger V. Tiegh and Trichoderma viride Pers. ex Fr. The treated Pinus massoniana Lamb. also showed good fire resistance with the oxygen indexes before and after leaching respectively at 20.45% and 13.64%, higher than those of the control group. It was concluded that the formulated protectant of this research had not only multiple functions of one dose, but also comprehensive resistances to decay, mold and fire, as well as strong leaching resistance.