Effect of extractions on dynamic mechanical properties of white mulberry Morus albaReportar como inadecuado




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* Corresponding author 1 MAB - Mécanique de l-Arbre et du Bois LMGC - Laboratoire de Mécanique et Génie Civil 2 Bois tropicaux - Production et valorisation des bois tropicaux 3 Department of Wood and Paper Science and Technology

Abstract : Vibrational properties of wood are affected by several parameters, of which extractives can be one of the most important ones. Wood for European musical instruments has been often studied, but traditional Middle Eastern ones had been left unnoticed. In this study white mulberry Morus alba L., the main material for long-necked lutes in Iran, was extracted by five solvents of various polarities water included. Free-free bar forced vibrations were used to measure longitudinal L loss tangent tanδ, storage elastic modulus E′ and specific modulus E′-γ in the acoustic range. Their anisotropy between the 3 axes of orthotropy was determined by DMA dynamic mechanical analysis. Native wood had a quite low EL′-γ but its tanδ was smaller than expected, and the anisotropy of tanδ and E′-γ was very low. Removal of extractives caused tanδ to increase and moduli to decrease. Acetone, the most effective solvent on damping despite a moderate extraction yield, increased tanδL by at least 20% but did not modify E′-γ as much. When used successively, its effects masked those of solvents used afterwards. Anisotropy of E′-γ was nearly unchanged after extraction in methanol or hot water, while tanδ was much more increased in R than in T direction. Results suggest that in white mulberry, damping is governed more by nature and localization of extractives rather than by their crud abundance.

Keywords : anisotropy damping coefficient DMA extractives vibrational properties white mulberry wood Morus alba L.





Autor: Aida Se Golpayegani - Iris Brémaud - Joseph Gril - Marie-France Thévenon - Olivier Arnould - Kambiz Pourtahmasi -

Fuente: https://hal.archives-ouvertes.fr/



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