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

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 ± 0.35^a

0.83 ± 0.12^{b c}

0.95 ± 0.19^{a b}

1.00± 0.22^{a b}

0.77± 0.20^c

Average wood failure ratio (%)²

80.0 ± 22.7^a

28.3 ± 25.5^b

59.3 ± 27.9^a

68.3 ± 29.9^a

70.6 ± 22.0^a

Judgment of test results (JAS)⁴

PASS

PASS

PASS

PASS

PASS