塗裝與乙醯化處理對雲杉材音響特性之影響

近年來，由於良質之樂器用木材資源日益枯竭，為了保護樂器及改善其音響特性，塗裝或化學方法處理己普遍地被樂器製造業所應用。本試驗以北美產雲杉為試材，探討硝化纖維素塗裝、聚胺基甲酸酯塗裝及乙醯化處理對其音響特性之影響。試驗所獲之主要結果如下：雲衫之音響特性，當木理傾斜角為0°時，未塗裝材較塗裝材為佳，但隨木理傾斜角之增加，則塗裝材之動彈性係數略大於未塗裝材。因為木材之音響性質主要取決於順木理方向之特性，故塗裝會對音響性質產生不利之影響，實用上應儘量減少塗膜之厚度；又乙醯化處理使雲杉之動彈性係數略為下降，同時亦使內部摩擦降低，而音響變換效率之綜合指標K值，則隨此處理而略為上升。

關鍵字

雲杉；硝化纖維素塗料；聚胺基甲酸酯塗料；乙醯化；音響性質

並列摘要

In recent years, the shortage of high quality musical wood has led to the development of several technical methods, including coating and chemical treatments, for use in protecting wood and improving its acoustic properties to meet minimum requirements for making musical instruments. The effects of nitrocellulose coating (NC), polyurethane coating (PU), and acetylation on the acoustic properties of Sitka spruce were investigated by using the vibrating reed method. The results indicated that: 1. When the grain angle of the wood specimen was 0°, the acoustic properties of uncoated Sitka spruce wood were better than those of specimens coated with NC or PU. However, the acoustic properties of the latter were better than the former as the grain angle increased. 2. Since the acoustic properties of wood are known to be inflnenced mainly by the characteristics associated with the parallel-to-grain direction, the thickness of coating should be as thin as possible when applied to the wood surface. 3. Values of dynamic Young's modulus of acetylated Sitka spruce slightly decreased and values of internal friction also decreased. However, the K value, the index of acoustic transfer efficiency, slightly increased as acetylation increased.

並列關鍵字

Sitka spruce ； NC lacquer ； polyurethane ； acetylation ； acoustic property

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塗裝與乙醯化處理對雲杉材音響特性之影響

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