モクザイ セッチャク ニ カンスル ケンキュウ ダイ4ポウ PVA ヘンセイ ニョウソ ジュシ セッチャクザイ ノ タイキュウセイ ニツイテ
Studies on the Wood Gluing(IV) : On the Durability of PVA-modified Urea Resin Adhesive
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It has been known from the previous paper that the polyvinyl alcohol-modified urea resin adhesive has the gap-filling property.
In the present paper, the durability of the polyvinyl alcohol-modified urea resin adhesive is discussed. Beech sapwood were glued with polyvinyl alcohol-modified urea resin adhesive and unmodified urea resin adhesive. Glue-line thickness were regulated in 60-100microns and 320-370 microns thick. These glued woods were exposed for five years to the repeating cycle consist of 2 weeks at 25℃ and 33 percent relative humidity and 2 weeks at 25℃ and 87 percent relative humidity.
After1-7, 9, 12, 16, 21, 39, 51 and 63 cycles were repeated, the block shear test was carried out with respective sample blocks.
Transition of glue-joint strength and wood failure for five yearsis shown Fig.1 and 2.
The glue-joint strength and wood failure when polyvinyl alcohol-modified urea resin adhesive was used were higher than those when the unmodified urea resin adhesive was employed.
In all cases, the glue-joint strength and wood failure increased through 4-9 cycles, and then they decreased along with exposure period.
Deterioration of polyvinyl alcohol-modified urea resin adhesive after 63 cycles was remarkably less in conparison with that of unmodified urea resin adhesive.
Bulletin of the Faculty of Agriculture, Shimane University
Departmental Bulletin Paper
Faculty of Life and Environmental Science