2. Material and methods
The raw material of this study consisted of walnut (Juglans regia
L.) shell and almond (Prunus amygdalusL.) shell which collected
from the field right after walnut and almond harvest in Sfejir and
Faroj, Iran, respectively and wood particles (a 60:40 blend) consist-ing of hornbeam (Carpinus betulusL.) and beech (Fagus orientalisL.)
species were obtained from a particleboard plant in Gorgan, Iran.
The adhesive was urea–formaldehyde (UF) which produced by a
local plant with characteristics given in Table 1.