Grading technology of China fir sawn lumber and its properties by melamine formaldehyde resin impregnation

• Main Authors: Bo-Yang Chang, 張柏揚
• Other Authors: 楊德新
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/3v9642

碩士 === 國立中興大學 === 森林學系所 === 107 === In order to improve the self-sufficiency rate of wood in Taiwan, in recent years, the effectively harvesting and utilization of domestic wood, and actively promote the certification system of domestic wood and bamboo products are encouraged. In addition, the qualities of the domestic wood is the key to develop the further application, therefore, the first part of this research is to investigate the sawing yield and the strength grading of the China fir wood, and the allowable stress is also evaluated to improve the utilization efficiency of the wood. In order to expand its applications and improve the durability for outdoor use, the second part of this study is to investigate the selected properties including mechanical properties, dimensional stability and anti-biological degradation properties of China fir wood modified by melamine-formaldehyde resin (MF) treatment. The result showed that the sawing yield was increased with the log diameter. However, the strength properties for visual graded China fir wood revealed a large variability in Class 1 to Class 3 grade, while they were graded more precisely by the E-grading rule and the GP (Grading parameter) grading rule. Comparing with two visual graded rules, CNS 14630 (2017) and CNS 14631 (2002), the result showed that the lumber with Class 3 and below grade had the higher distribution ratio according to CNS 14631 (2002) inspection. In conclusion, the relationship between the log qualities and lumber properties showed that the higher the grade of log presented, the better the visual properties and strength of lumber were performed. On the other hand, the mechanical properties including compressive strength, hardness, shear strength and bending properties of China fir wood were increased after treated by MF. The result also revealed that the hardness of China fir wood had the highest improvement and followed by the compressive strength. On the contrary, the increments of bending properties and shear strength were not obvious. In terms of the dimensional stability of the treated China fir wood, the water absorption and volumetric swelling coefficient both decreased with the weight percent gain of the MF penetration increased, meanwhile, the anti-swelling efficiency of treated China fir wood increased. Furthermore, the result of the termite resistance test showed that the mass loss of China fir wood was reduced after treated by the MF resin, and the highly termite mortality rate was presented in the W25 and W35 groups. Furthermore, the results of decay resistance test indicated that the mass loss was also reduced for the MF treated China fir wood no matter tested by brown rot fungi (L. sulphureua, F. pinicola) or white rot fungi (L. betulina, T. versicolor). Finally, after accelerated weathering test, the China fir wood treated with MF resin had a better surface properties performance, including of surface color change, roughness and wettability than untreated one.