Penetration depth of adhesive depending on wood anatomical structure
2014
Laiveniece, L., Latvia Univ. of Agriculture, Jelgava (Latvia) | Morozovs, A., Latvia Univ. of Agriculture, Jelgava (Latvia)
Wood is one of the key raw materials that are used in constructions. Thereby it is very important to understand all the processes that are involved in bonding technology. Adhesive penetration into wood at bond-line is influenced by many factors such as wood, adhesive and process factors. The objective of the present paper is comparison of the polyurethane (PU) glues penetration depth into Scots pine ( Pinus sylvestris L.) and Norway spruce ( Picea abies L.Karst) wood depending on the wood anatomical structure. The bond-line width of cured adhesive and the anatomical structure of wood were determined using fluorescence microscopy. From investigation of wood anatomical structure results were obtained with close correlation between tracheid width and early or late wood width. The calculated surface energy of Norway spruce was higher than of Scots pine wood due to higher measured surface roughness. Good correlation was obtained between Lifshitz–van der Waals component of surface free energy and wood moisture content (R = 0.94153 for Norway spruce, R = 0.77721 for Scots pine). The obtained results shown that the penetration depth of adhesive was deeper in Norway spruce wood (356.82±47.41 μm) due to longer average tracheids width, thickness and length than in the case of Scots pine (56.95±27.60 μm).
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