Effects of different pressures and veneer moisture content in adjacent layers on properties of PUF bonded plywood

Figures & data

Figure 1. Scheme of the formation of the plywood.

Table 1. Technological parameters for manufacturing the plywood specimens.

Code of specimens	Pressing pressure [MPa]	Moisture content [%]		Pressing temperature [°C]	Pressing time [seconds]	Adhesive spread [g/m^2]
		1, 3, 5 layers	2, 4 layers
0.8 M	0.8	2	7	135	600	150
1.2 M	1.2
0.8 C	0.8	5
1.2 C	1.2

Table 2. The physical properties of the veneer and plywood.

Code of specimens	Number of veneers	MC of veneer [%]	MC of plywood [%]	Density of plywood [kg/m^3]
0.8 C	1, 2, 3, 4, 5	4.7 (0.5)	8.1 (0.1) A	497 (17) A
1.2 C	1, 2, 3, 4, 5	4.8 (0.6)	8.2 (0.2) A	511 (19) A, B
0.8 M	1, 3, 5	2.0 (0.8)	8.7 (0.4) B	508 (20) A, B
	2, 4	7.0 (0.8)
1.2 M	1, 3, 5	2.0 (0.7)	8.6 (0.4) B	523 (21) B
	2, 4	7.0 (1.0)

Means with the same letter in column do not differ statistically by the Tukeýs test (α = 0.05). Numbers in parentheses represent standard deviation.

Figure 2. the density profile of tested specimens.

Table 3. Bending properties of longitudinal and transverse specimens.

Code of specimens	MOR [N/mm^2]		MOE [N/mm^2]
	Longitudinal	Transverse	Longitudinal	Transverse
0.8 C	55.4 (10.8) A	28.5 (6.5) A	7270 (790) A	2464 (335) A
1.2 C	45.9 (18.3) A	26.5 (6.1) A	6453 (1266) A	2386 (505) A
0.8 M	53.7 (10.6) A	26.5 (10.4) A	6934 (752) A	2365 (554) A
1.2 M	54.4 (16.5) A	20.3 (9.1) A	6655 (1672) A	2191 (601) A

Means with the same letter in column do not differ statistically by the Tukeýs test (α = 0.05). Numbers in parentheses represent standard deviation.

Figure 3. Bonding quality and wood failure of specimens in three different exposures (Exposure 1 – conditioning 20 °C and 65% RH; Exposure 2 – soaking in water 20 °C for 24 h; Exposure 3 – boiling in water for 6 h and cooling in water 20 °C at least 1 h).

Table 4. The bonding quality and wood failure of plywood specimens.

Code of specimens	Bonding quality [N/mm^2]			Wood failure [%]
	Exposure 1	Exposure 2	Exposure 3	Exposure 1	Exposure 2	Exposure 3
0.8 C	1.6 (0.4) A	0.9 (0.4) A	0.9 (0.3) A	33 (26) A	23 (12) A	23 (10) A
1.2 C	1.5 (0.5) A	0.9 (0.3) A	0.8 (0.3) A	43 (28) A, B	28 (15) A	42 (25) B
0.8 M	1.5 (0.5) A	0.9 (0.3) A	0.7 (0.2) A	29 (11) A	27 (9) A	25 (20) A
1.2 M	1.8 (0.5) A	1.0 (0.2) A	0.9 (0.2) A	57 (24) B	33 (20) A	42 (20) B

Means with the same letter in column do not differ statistically by the Tukeýs test (α = 0.05). Numbers in parentheses represent standard deviation.