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 2 Fibrillated bark slurry adhesive composition and bonding quality of radiata pine plywood from the continuous 72-h boiling test (JAS)

Adhesives	CF¹	1-1	1-2	1-3	1-4	1-5	1-6
Mass ratio
PF resin (solids)	100	70	60	50	40	30	20
Fibrillated bark slurry (solids)	0	30	40	50	60	70	80
Wheat flour	24	0	0	0	0	0	0
Other solid components	22	0	0	0	0	0	0
Total solids content (%)	55	36	35	30	27	24	21²
Viscosity (Pa s) (23 °C)	1.4	1.7	1.6	2.0	1.9	2.0	2.9
Reactive components in adhesive (%)
PF resin contents	32.0	25.2	21.0	15.0	10.8	7.2	4.2
Polyflavanoids contents	0.0	5.7	7.4	7.9	8.5	8.8	8.8
Bonding test results
Number of panels	4	4	4	4	6	4	4
Number of specimens	32	32	32	32	48	32	32
Average of shear strength (MPa)³	0.84 ± 0.21b	1.06 ± 0.25a	1.07 ± 0.32a	0.88 ± 0.25b	0.82 ± 0.21b	0.81 ± 0.19b	0.77 ± 0.22b
Average wood failure ratio (%)³	87.2 ± 9.9a	72.2 ± 35.3abc	76.9 ± 27.2ab	65.3 ± 37.6bc	56.0 ± 26.0bc	52.2 ± 39.0c	78.1 ± 20.7a
Judgment of test results (JAS)⁴	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
²This value was not determined but estimated on the basis of the viscosity in the previous study [13]
³Results are given as the mean ± standard deviation. ANOVA for analysis of variance showed that the means are significantly different (p < 0.001). Same letters within a row are not significantly different as determined by the Tukey’s test (p < 0.05)
⁴“PASS” means met the criteria of JAS