Investigation the fire hazard of plywoods using a cone calorimeter

A high-efficiency fire retardant composition was prepared with dicyandiamide, phosphoric acid, boric acid, borax, urea and magnesium sulfate and it was used to process veneers which were then to prepare the plywood. Meanwhile, heat release and smoke release from combustion of plywood were tested by a cone calorimeter, including heat release rate, mass loss rate, CO yield, CO2 yield and oxygen consumption. Results showed that the plywood with this fire retardant treatment had the better flame-retardant performance and smoke suppression effect as well as the stronger char-forming capability compared to plywood without fire retardant treatment. The average heat release rate, total heat release, average effective heat of combustion, total smoke release, CO yield and oxygen consumption of the plywood with fire retardant treatment were decreased by 63.72%, 91.94%, 53.70%, 76.81%, 84.99% and 91.86%, respectively. Moreover, the fire growth index of plywood treated by fire retardant was relatively low (3.454 kW·m-2·s-1) and it took longer time to reach the peak heat release rate, accompanied with slow fire spreading. The fire performance index was relatively high (0.136 s·m2·kW-1) and it took longer time to be ignited, thus leaving a long time for escaping at fire accidents. The fire hazard of plywood with fire retardant treatment was low, and its safety level was high.

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.

Development of mimosa tannin-based adhesive cross-linked by furfuryl alcohol-formaldehyde and epoxy resins

A furfuryl alcohol-formaldehyde resin was synthesized as a crosslinker in our laboratory to develop a mimosa tannin-based adhesive with good water resistance. 13C nuclear magnetic resonance and matrix-assisted laser desorption ionization time-of-flight mass spectroscopy indicated that furfuryl alcohol reacted with formaldehyde under acidic conditions and that–CH (–OH) – groups to be the ones involved in the crosslinking of mimosa tannin-furfuryl alcoholformaldehyde adhesive (TFF). The wet shear strength of TFF-bonded plywood suggested that the cured TFF adhesive was better than mimosa tannin-furfuryl alcohol (TF) adhesive. The water resistance of TFF adhesive cross-linked with 9% epoxy resin was also higher than those of TFF and TF adhesives.

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.