Plywood adhesives using PF resin with fibrillated bark slurry from radiata pine ( Pinus radiata D. Don): utilization of flavonoid compounds from bark and wood. IV

Journal of Wood Science

Official Journal of the Japan Wood Research Society

Table 3 Fibrillated bark slurry adhesive composition and bonding qualities of hinoki and karamatsu plywoods from the continuous 72-h boiling test (JAS)

Adhesives	CF¹	1	2	3	CF¹	1	2	3
Mass ratio
PF resin (solids)	100	60	50	40	100	60	50	40
Fibrillated bark slurry (solids)	0	40	50	60	0	40	50	60
Wheat flour	15	0	0	0	15	0	0	0
Other solid components	22	0	0	0	22	0	0	0
Total solids content (%)	55	34	30	27	55	34	30	27
Viscosity (Pa s) (23 °C)	1.6	1.9	1.6	2.1	1.7	1.9	1.6	2.1

Bonding test results
Plywood species	Hinoki (Japanese cypress)				Karamatsu (Larix species)
Number of panels	4	4	4	4	4	1	2	3
Number of specimens	32	32	32	32	32	8	16	24
Average of shear strength (MPa)²	1.02 ± 0.37a	1.18 ± 0.28a	1.24 ± 0.37a	1.17 ± 0.39a	1.05 ± 0.33a	0.98 ± 0.34a	0.86 ± 0.36a	0.87 ± 0.24a
Average wood failure ratio (%)²	93.8 ± 5.5a	23.1 ± 33.2c	21.9 ± 25.3c	47.5 ± 35.6b	94.4 ± 8.4a	95.0 ± 8.7a	21.8 ± 17.6b	47.5 ± 30.3b
Judgment of test results (JAS)³	PASS	PASS	PASS	PASS	PASS	PASS	PASS	PASS

¹“CF” means “Commercial formulation” refers to a composition of a commercial adhesive using PF resin for plywood
²Results are given as the mean ± standard deviation. ANOVA for analysis of variance showed that the means are significantly different (p < 0.001). The same letter within a row are not significantly different as determined by the Tukey’s test (p < 0.05)
³“PASS” means met the criteria of JAS