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熱處理對壓縮木材性質之影響
Effect of Heat Treatment on the Properties of Compressed Wood
摘要
本研究探討熱處理對壓縮木材性質之影響，以杉木爲試材，於徑向進行壓縮加工並經熱處理後，進行回復、吸濕與吸水等物理性質試驗，靜曲、硬度與剪斷等機械性質試驗，及常態與耐水等膠合性質試驗。 壓縮木材之回復度隨壓縮量之增加、熱處理溫度之增高與時間之增長而降低。同時其吸濕吸水後之含水率與厚度膨脹率之增加，明顯地受熱處理溫度與時間之影響。 壓縮木材之靜曲強度、硬度與剪斷強度均隨壓縮量之增加而明顯增大，除了壓縮量67%時，硬度不因熱處理之影響而降低外，其餘者於任一壓縮量下，熱處理者之強度性質均較無熱處理者降低。 膠合試驗之結果顯示任一壓縮量之壓縮木材無論是否進行熱處理均具有良好之常態膠合性能，而壓縮量增大時，熱處理者之耐水膠合強度與木破率，與無熱處理者較爲接近，可獲得較令人滿意之耐水膠合性能。
並列摘要
In this study I investigated the effect of heat treatment on the properties of compressed wood. China fir (cunninghamia lanceolata) wood was compressed in the radial direction and then heat treated. Physical properties (such as recovery of set, hygroscopicity, and water absorption), mechanical properties (such as hardness, static bending strength, and shear strength), and gluing properties (such as normal and water-resistance bonding strength) of the compressed wood were examined afterward. The recovery of set of compressed wood decreased with increases in compression set, heat treatment temperature, and time. The changes of moisture content and thickness swelling in the hygroscopicity and water absorption tests were evidently affected by treatment temperature and time. The hardness, static bending strength, and shear strength of compressed wood increased with the increasing compression set. However, heat-treated compressed wood had lower mechanical properties than did, untreated compressed wood, except for the hardness of compressed wood in the 67% compression set. Results of bonding strength test showed that normal gluing properties were good for all compressed woods irregardless of heat treatment, and the water-resistance bonding strength and wood failure of heat-treated compressed wood in larger compression sets approached those of untreated compressed wood.