Document Type : Research Paper
Authors
1
Graduate M.Sc. Student, Faculty of Natural Resources, University of Zabol, Zabol, I.R. Iran
2
Assoc. Prof., Faculty of Natural Resources, University of Zabol, Zabol, I.R. Iran
3
.Assoc. Prof., Faculty of Natural Resources, University of Zabol, Zabol, I.R. Iran
4
Assoc. Prof., Faculty of Scince, University of Zabol, Zabol, I.R. Iran
5
Graduate M.Sc. Student, Faculty of Natural Resources University of Zabol, Zabol, I.R. Iran
Abstract
The purpose of this study was to investigate the effect of urea as additive on reduction of formaldehyde emission and internal bonding strength (IB) improvement. Experimental boards were made using wood particles and urea formaldehyde adhesive. Pressure (25.26 kg/cm2), temperature (200 ˚C) and press time (7 minutes) were considered as constant factors. The wood particles with urea formaldehyde resin were pressed in three levels (8, 9 and 10 wt%) and urea additive at five levels (0, 3, 6, 9 and 12 wt%). Urea powder as additive was added in the two forms: to the particles and to resin solution. Test specimens for formaldehyde emission and IB were prepared from experimental boards following standers AS/NZS 4266.16 and EN 326-1, respectively. Formaldehyde emission was determined according to the Japanese standard desiccator method. In this study, the concentration of the formaldehyde gas reached the E2 class. The results showed that the reduction of urea formaldehyde resin decreases the release of formaldehyde from particleboard. In addition, the results illustrated that by decreasing the percentage of the urea additive in particleboard, both formaldehyde releasing also the formaldehyde emission ere reduces. Furthermore, IB was increased (higher than standard) by adding urea powder to resin solution. The presence of urea at the surface of the wood chips prevents the formation of good connections between adhesive and wood particles.
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