Proceedings e report - Firenze University Press

WOOD SCIENCE FOR CONSERVATION OF CULTURAL HERITAGE
Table 2- Dimensions and number of the experimental samples in each repetition and treatment
Type of the Test
Dimension (mm)
Length Width Thickness
327
Number of
Samples in
Each
Repetition
Modulus of Rupture and
Modulus of Elasticity
250 50 10 4 12
Internal Bonding 50 50 10 4 12
Thickness Swelling 50 50 10 4 12
Number of
Samples in Each
Treatment
3. Discussion and conclusion
In this study, particleboard was made from four different combinations of pomegranate wood and
poplar (P. nigra) wood with two resin contents of 10% and 12% and two press times of 4 and 5
minutes. The four wood combinations were as follows: 100% pomegranate wood; 75% pomegranate
wood and 25% poplar wood; 50% pomegranate wood and 50% poplar wood, and 100% poplar wood
as control sample. The results of physical and mechanical tests performed on the manufactured
particleboards may be discussed as follows and reach to following conclusions.
Considering the results, it was observed that when the press time increased from 4 to 5 minutes, the
MOR of the boards decreased meaningfully (Fig. 1). Increase of press time from 4 to 5 minutes not
only has deteriorated the adhesive quality of resin and wood but also caused thermal destruction of
wood particles in surface layer. On the other hand, the mutual effects of resin content value and the
press time on MOR and the MOE of the boards are meaningful and when the resin content is 4% when
the press time is increased from 4 minutes to 5 minutes, the MOR and the MOE of the boards are
decreased (Fig. 1, 2). This indicates that during the press time the resin particles have undergone more
thermal destruction and when the resin content is 12%, the existence of more resin particles on the
board surface will decrease the MOR significantly.
MOR
Fig. 1-Mutual effects of resin content and press time on modulus of rupture
The results of this study also showed that when poplar wood particles were added to the wood
combination used for making the particleboards, the MOR and the MOE of the boards would increase
and the highest MOR was gained when the wood combination was purely (100%) poplar particles.
Since the pomegranate particles have higher specific weight than poplar particles, when poplar wood
is added to the combination the compression coefficient of particles in the mat (especially on its
surface) is increased, therefore addition of poplar wood particles improves the MOR and the MOE. In
the meanwhile, even when pomegranate wood is used 100% in making the particleboards, the MOR
and the MOE are higher than standard value.
The results of this study shows that increase in resin content will improve the IB of the boards because
when more resin is used, more efficient connections are created between the particles and thus, higher