WOOD RESEARCH Volume 67, Number 3, 2022
Bengang Zhang, Liping Yu, Qiaoyan Zhang, De Li, Yuan Tu, Guoming Xiao, Zhigang Wu, and Jiankun Liang

Effects of fire retardants on mechanical properties and water resistance of Pinus massoniana particleboard

Pinus massoniana Lamb. wood particleboards processed by inorganic and organic fire retardants of two densities were prepared by isocyanate and MUF resin. Variations of internal bonding strength (IB), modulus of rupture (MOR), modulus of elasticity (MOE) and thickness swelling rate (TS) of particleboard were observed. Results demonstrated decreasing of IB from 0.81 MPa to 0.42 MPa and 0.36 MPa, MOR from 17.3 MPa to 12.5 MPa and 12.3 MPa, MOE from 1840 MPa to 1328 MPa and 1117 MPa, and increasing of TS from 5.2% to 15.1% and 11.2%, respectively, for the treated MUF particleboards of density 0.65 g.cm-3. Similarly, decreasing of IB from 0.93 MPa to 0.66 MPa and 0.64 MPa, MOR from 16.2 MPa to 10.6 MPa and 12.1 MPa, MOE from 1246 MPa to 1573 MPa and 1466 MPa, and increasing of TS from 6.7% to 7.1% and 6.0%, respectively, when isocyanate adhesive was used. The similar changes were showed when the density of particleboard was 0.75 g.cm-3. Improving density of particleboard appropriately and decrease density difference between the surface to chip layers could make the profile density curve tend to be stable, which could get a relatively high mechanical strength and water resistance. Synergistic effects between isocyanate and fire retardants was confirmed. The particleboard prepared with isocyanate was obviously superior to that prepared with MUF resin in all performances.

WOOD RESEARCH Volume 66, Number 6, 2021
Zhigang Wu, Xue Deng, Lifen Li, Liping Yu, Jie Chen, Bengang Zhang, Xuedong Xi, and Qiaoyan Zhang

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.

WOOD RESEARCH Volume 62, Number 2, 2017
Hong Yun, Kaifu Li, Chuangshuang Hu, and Dengyun Tu

Adsorption and fixation of soluble fire retardancy in Populus russkii and Cunninghamia lanceolata

Flame retardant treatment is a common method of wood preservation. However, the factory usually uses the same approach to all the wood, but lack of targeted so as to cause waste. This study used poplar and Chinese fir as the species investigated. These species were dipped with boron-nitrogen-phosphorus (B-P) fire retardant. The influences on material loading of processing method, concentration of fire retardant, and drying method were investigated. The contents of B and P were tested by inductively coupled plasma optical emission spectrometry (ICP-OES), after distilled water washing and ultrasonic washing. The results showed that the volume loading increased with the concentration of fire retardant. Freeze-drying can noticeably improve the volume loading, and the impact of the drying method was more notable on poplar than on Chinese fir. The fixation effect of the B and P in poplar was lower by ultrasonic washing than that was by distilled water washing. The fixation effect was opposite in the Chinese fir. Vacuum process was more suitable for the poplar (hardwood), and vacuum-pressure process was
more suitable for the Chinese fir (soft wood).

WOOD RESEARCH Volume 64, Number 1, 2019
Patrícia Kadlicová, Linda Makovická Osvaldová, Juraj Jancík, and Milan Gaff

Effect of thermal and retarding treatment on flammability rate of tropical tree species

Wood is integral to the construction industry despite the fact that it is a highly flammable material. Due to thermal stress, it is subject to the process of pyrolysis. However, not every type of wood burns the same. This dissimilarity is caused by the changes in its internal structure. Flammability rate of tree species can be modified by means of thermal modification, i.e. change in its internal structure or by using coating compositions which form a fire-protecting layer on its surface. The paper comprises a testing and an evaluation of iroko wood which is predominantly used as floor covering and cladding material for building structures. The authors focus on determining the connection between the structure of this exotic tree type and the eventual thermal degradation (burning course, significant changes, amount of material burnt, etc.) of the samples. Small size samples were used during laboratory measurements. Their width and thickness were approximately the same as for commonly used cladding boards. The data obtained in the laboratory have been processed, transformed into evaluation criteria and connected with theoretical knowledge, creating an overview of its eventual flammability. Laboratory test results prove low flammability rate of test samples. Mass loss was an important criterion. Thermal treatment, which changes the internal structure and thus improves its properties (T group; test samples), had no significant effect on the eventual flammability. On the other hand, the flammability rate of samples was better when using a fire retardant (R and TR group; test samples), because the retardant lowers the flammability by more than half.