WOOD RESEARCH Volume 70, Number 4, 2025
DOAN VAN DUONG and MASUMI HASEGAWA

NONDESTRUCTIVE PREDICTION OF BENDING STRENGTH OF PINUS MASSONIANA LAMB. LOGS AND SMALL CLEAR SPECIMENS USING STRESS-WAVE MEASUREMENTS

The main objective of this study was to investigate the relationships between stress-wave velocity measured in logs and small clear specimens and the bending strength of Pinus massoniana trees planted in northern Vietnam. Stress-wave velocity (SWVL) and green wood density (WDL) were measured on logs collected from different heightlevels of 23-year-olds P. massonianatrees. Stress-wave velocity (SWVS), wood density (WDS), and bending strength (MOR) were subsequently determined on small clear specimens prepared from the logs. Regression analyses revealed significant correlations between SWVL and MOR (r = 0.73, P < 0.001) and between SWVS and MOR (r = 0.80, P < 0.001). These results show that stress-wave velocity measurements, whether taken on logs or small specimens, are effective for segregating P. massoniana lumber resources based on MOR. A more accurate prediction of strength was obtained when stress-wave velocity and log or specimen wood density were used together to calculate the dynamic modulus of elasticity of logs (DMOEL) or specimens (DMOES), respectively. The correlation coefficients were 0.82 (P < 0.001) between DMOEL and MOR, and 0.93 (P < 0.001) between DMOES and MOR.

WOOD RESEARCH Volume 70, Number 1, 2025
DOAN VAN DUONG, VAN HUNG HOANG, MASUMI HASEGAWA, and EVGENII SHARAPOV

THE INFLUENCE OF TREE AGE AND RADIAL POSITION ON THE STRESS-WAVE VELOCITY AND TIMBER PROPERTIES OF PINUS MASSONIANA LAMB. PLANTED IN VIETNAM

The main objective of this study is to investigate the influence of tree age and radial position on the structural properties, asair-dry density (AD), modulus of rupture (MOR), modulus of elasticity (MOE) and the stress-wave velocity measured on small specimens (SWVS). Results of analysis showed a highly significant effect of age and radial position on the SWVS, AD, MOR, and MOE. Stress-wave velocity and wood property traits tend to increase with increasing tree age. The SWVS and selected wood properties near the pith were significantly lower than those near the bark. Mean MOR and MOE of the timber had significantly (P<0.001) relationships with SWVS (r = 0.75 and 0.91, respectively), although in the case of MOR a model based on AD alone is slightly better (r = 0.79). There were also significant relationships of acoustic velocity measured in standing trees (SWVT) with mechanical properties measured destructively in small specimens implying that stress-wave method has a good potential for measuring static bending properties of P. massonianaplanted in Vietnam

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 4, 2021
Jianhua Lyu, Cheng Guan, Xianwei Li, and Ming Chen

Effects of stand density on turpentine terpene components and resin duct morphological structure of Pinus massoniana

The influence of stand density on the resin duct morphological structure and terpene components of Pinus massoniana were studied. The resin duct morphological characteristics and the relative content of the terpene components were investigated by microscopy and gas chromatography-mass spectroscopy, respectively. The experimental results revealed that there was a specific correlation between the stand density and resin duct area, resin duct diameter, and the relative contents of main terpene components in the turpentine extracts. Additionally, the relative contents of β-pinene and (+)-camphene were positively correlated with stand density, with correlation coefficients of 0.8208 and 0.5539, respectively. In contrast, the relative contents of (+)-longifolene and (+)-longicyclene were negatively correlated with stand density, with correlation coefficients of -0.5750 and -0.7726, respectively, and α-pinene, β-caryophyllene, and (+)-α-longipinene had no correlation with stand density. The relative content of (+)-α-pinene was negatively correlated with the relative contents of both (+)-longifolene and (+)-longicyclene, with correlation coefficients of -0.8770 and -0.8914, respectively. There were positive correlations between the relative contents of (+)-longifolene and (+)-longicyclene with correlation coefficient of 0.9718, (+)-longifolene and (+)-α-longipinene with correlation coefficient of 0.8399, β-caryophyllene and (+)-α-longipinene with correlation coefficient of 0.9360, and (+)-longicyclene and (+)-α-longipinene with correlation coefficient of 0.8626.