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Official Journal of the Japan Wood Research Society

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Table 2 Bark particle adhesive composition and bonding quality from the continuous 72-h boiling test (JAS)

From: Development of bark-based adhesives for plywood: utilization of flavonoid compounds from bark and wood. II

Adhesives1 CF-A 1-1 1-2 1-3 1-4
Mass ratio
 PF resin (solids) 100 70 60 60 50
 Bark particles 0 30 40 28 35
 Wheat flour 36 0 0 12 15
 Other solid components 36 0 0 0 0
Total solids content (%) 55 40 37 40 35
Viscosity (Pa·s) (23 °C) 3.2 2.0 2.7 2.2 1.8
pH3 nd nd nd nd nd
Gelation time (min) (135 °C)3 nd nd nd nd nd
Reactive components in adhesive (%)
PF resin contents 32.2 28.0 22.2 24.0 17.5
Polyflavanoids contents 0.0 5.1 6.2 4.7 5.2
Bonding test results
Number of panels 4 3 4 5 4
Number of specimens 32 24 28 40 32
Average of shear strength (MPa)2 1.06 ± 0.35a 0.83 ± 0.12b c 0.95 ± 0.19a b 1.00± 0.22a b 0.77± 0.20c
Average wood failure ratio (%)2 80.0 ± 22.7a 28.3 ± 25.5b 59.3 ± 27.9a 68.3 ± 29.9a 70.6 ± 22.0a
Judgment of test results (JAS)4 PASS PASS PASS PASS PASS
  1. 1“CF-A” means “Commercial formulation A” and refers to the formulation of a commercial adhesive for plywood using PF resin A
  2. 2Results are given as the mean ± standard deviation. ANOVA showed that the means are significantly different (p < 0.001). Means having the same letter (a, b, c) within a row are not significantly different as determined by the Tukey’s test (p < 0.05)
  3. 3“nd” means “not determined”
  4. 4“PASS” means met the criteria of JAS