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                      THE DENSITY OF LOPVL BOARDS

            S. Abdul Hamid, W. A. Wan Tarmeze, A. Khairul, U. Mohd Khairun Anwar,
                                      M. Ab Jalil, & O. Arshad
          Forest Research Institute Malaysia (FRIM), 52109 Kepong, Selangor Darul Ehsan
                                   (Project No. 03-03-10-SF0011)

      The objectives of the study were to determine the specific gravity (SG) variation of two
      different qualities of oil palm veneers, i.e. superior (S) and inferior (I) and to evaluate effect
      of densities from three categories of laminated oil palm veneer lumber (LOPVL) boards,
      namely high (100 % S), medium (60 % S + 40 % I) and low (20 % S + 80 % I). The results
      of the study can be used as a basis to evaluate the proposed method of segregating S and
      I veneers which has been derived from the current industrial practice in separating oil palm
      trunk (OPT) veneers based on the type of peeling machine used.


Oil palm (Elaeis guineensis Jacq.) was introduced to Malaysia in early 1900’s. Today, oil palm
planted areas in Malaysia has exceeded 4 million ha (MPOB 2007). With this large number of
oil palm plantation hectarage, it is estimated that the number of oil palm trunks (OPT) will be
available at any time as a result of replanting activities. It has been estimated that replantation
of 100,000 ha of oil palm trees each year will produce 13.6 million OPTs annually (Mohd.
et al. 2003). Oil palms are usually felled after the age of 25 years. Leaving the trunks in
the field without further processing will physically hinder the process of planting new crops.
The practice of disposing OPTs by open-air burning has been considered unacceptable as it
pollutes the air and affects the environment. In the past few years, veneers from OPTs were
found appropriate for making laminated veneer lumber (LVL) which is one of the most common
structural composite lumbers (SCL) products developed by the timber industry. The composite
lumber, known as laminated oil palm veneer lumber (LOPVL) in this study, is fabricated from
layers of OPT veneer with the grain orientations arranged parallel in all layers. This contradicts
the plywood where the grain orientations of adjacent layers is perpendicular. This study also
evaluates the potential of LOPVL to be converted into value-added products such as pallets,
furnitures and garden/landscape structures.
       The project commenced with determining the physical properties, namely specific
gravity (density) and moisture content of OPT veneers which will be the base materials for the
fabrication of LOPVL. It is a well known fact that the physical properties of a palm trunk varies
significantly across the cross section and along the height of the trunk. Thus, this would pose a
challenge to the LOPVL manufacturer to produce LOPVL with acceptable uniformity in physical
and mechanical properties. It is therefore proposed to categorise the OPT veneers into two
categories, i.e. superior (S) from the outer portion of the trunk, and inferior (I) from the inner
portion. The categories are derived from the current practice by the LOPVL (and the oil palm
plywood) manufacturers that separates the veneers based on the type of peeling machine

                                    MATERIALS AND METHODS

Five oil palm trunks from Felda Trolak were converted into veneers using two types of rotary
peeling machines, namely the normal and the chuckless. Each OPT was first peeled using
the normal peeling machine until the billet (OPT being peeled) was left with diameter of
approximately 12 inches and the veneers obtained were grouped as superior (S). Next, the

billet was further peeled using the chuckless peeling machine and the veneers obtained were
labelled as inferior (I). The process continued until the billet diameter reached 4 inches and the
remaining billet was discarded as core (see Figure 1). The approximate size of each veneer is
shown in Figure 2. The physical properties of the veneers for each sample were measured at
both ends of the veneer (marked as ‘A’). The average results represented the properties of the
veneer (B) which was later being used to make LOPVL.

                                                                          12” ( I)

                                                                           4” ( C )
                                                        S                                           S
           S     I     C     I       S

                                            (Note: C = Core)
                      Figure 1 Determination of superior (S) and inferior (I) veneer

          F igur e 1: Determ ination of super ior (S) and infe r ior (I) veneer . (Note: C = Cor e)
        Three groups of LOPVL (based on the arrangement and percentage of S and I veneers
used) were fabricated, namely high (H), medium (M) and low (L) (Figure 3). In H group, veneers
were 100 % of S quality. As for the M and L groups, the combinations were 60 % S + 40 % I
and 20 % S + 80 % I. The final thickness of the board (after pressing) was targeted at 27±2.0
mm. The board manufacturing pressure, temperature and time were set at 2000 psi, 110 ºC
and 20 min respectively. The resin used was urea formaldehyde (UF)—purchased from a local
glue supplier. The board fabrication process was taken at Kin Heng Timber Industries Sdn Bhd
in Chemor, Perak. The boards were then trimmed to 1200 mm × 600 mm (length × width) with
fibers orientation parallel to the board length. Four samples were taken from several locations
from each board for physical tests.

                                                                             (Note: the drawing is not to scale)

                                 Figure 2 The size of each OPT veneer

          High (H)                           Medium (M)                               Low (L)
                                 (Note:      = S veneer,       = I veneer)
                            F igur e 3. Th r ee quality gr oups of L OPVL
                                 Figure 3 Three veneer,
                             (Note:          = S quality groups of= I veneer)

                                   RESULTS AND DISCUSSION

The SG mean of OPT veneers and LOPVL boards are tabulated in Table 1 and Table 2 . The
SG distributions are shown in Figure 4 and Figure 5. For S veneers, the SG ranged from
0.369 to 0.666 at average of 0.479. The I veneers ranged from 0.271 to 0.487 at average
of 0.385. ANOVA result showed that SG mean of S veneers was significantly different from
that of I veneers. The result has similarity with the previous studies carried out where the SG
at the cross-section of OPT decreased significantly across the diameter towards the inner
region of the trunk. According to Mohd et al. (1991), the SG of a 27-year-old OPT at the outer
region was higher while it decreased as it approached to the middle region. The SG values
decreased from 0.51, 0.32 to 0.28 across the cross section, ranging from outer to the middle
of the cross section. Lim and Khoo (1986) explained that this is influenced by the number of
vascular bundles appeared per unit square where it decreases towards the centre of the cross
       However, the veneer SG distribution (Figure 4) revealed that there was an overlapping
area (the area between ‘mean S’ and ‘mean I’) where the SG values can equally belong to S
and I veneers. This overlapping situation would not have happened if all the veneers were from
the same unit of OPT because (as has been discussed above) the veneers were taken from
regions away from the core of the trunk (the S veneers) which have always possess greater
SG values than those from sections nearer to the core (the I veneers). However, since the
veneers were from five different OPTs (which could have different SG values), it was possible
that the SG values of a S veneer were similar to I veneer from other OPT. As a result, it is
possible that LOPVL boards of different grades (e.g. high and medium) fabricated from veneers
from the overlapping area to have similar SG values.
       The SG means (Table 2) for the three different groups of LOPVL boards were found
significantly different where the high group recorded 0.655 (ranged from 0.617 to 0.703), medium
at 0.577 (0.485 to 0.679) and low at 0.505 (0.408 to 0.575). Nevertheless, the consequences of
the overlapping problem stated above can be clearly observed in Figure 5 where LOPVL board
from the medium group contained similar SG value to that of from the high and low group.
                   Table 1 Specific gravity of superior (S) and inferior (I) OPT veneers

                  Veneer Group               SG                   Standard Deviation
                       S                    0.479   a
                        I                   0.385   b

                     Note: Means with the same letter are not significantly different at α= 0.05
                                        by Duncan - Walller-Duncan Test

           Table 2 Specific Gravity of High (H), Medium (M) and Low (L) LOPVL

           LOPVL Group                         SG                       Standard Deviation
                    H                         0.655a                         0.0235
                    M                         0.577   b
             L                 0.505                  c
      Note: Means with the same letter are not significantly different at α= 0.05
                             by Duncan - Walller-Duncan Test

) 0 .7 0
G                                                                                            S u p e r io r ( S )
t                                                                                            In f e r io r ( I)
v0 .6 0
c 0 .5 0                                                                                  Mea n(S) = 0.479
                                                                                             Overlap Area
  0 .4 0

                                                                                          Mea n(I) = 0.385
  0 .3 0

  0 .2 0

            0               20          4 0                60        OPT Veneer Samples
                                                                       8 0        10 0

                Figure 4 SG distribution of superior (S) and inferior OPT veneers
                  F igur e 4. SG distr ibution of Super ior (S ) and In fer ior O PT Veneer s

 ) 0.8
 G                                                                                        High
 y                                                                                        Med
 v 0.7
 a                                                                                        Low
 i                                                                                 Mea n (H) = 0.655
 c 0.6
 p                                                                                 Mea n (M) = 0.577

    0.5                                                                            Mea n (L) = 0.505


            0           2        4     6          8             10   LOPVL14
                                                                     12          16

  Figure 5 SG distribution of high (S) medium (M) and low (L) LOPVL boards
  F igur e 5. SG distr ibution of Hig h ( S) M edium (M ) and Low (L) L OPVL B oar ds


OPT veneers were being categorised into two categories, namely superior (S) and inferior (I)
and the SG variations between the two groups were evaluated in this study. Results showed
that the current fabrication method of LOPVL boards will produce inconsistent quality boards,
even within the same group of boards. The properties between boards will vary greatly under
the same quality group. Thus, it is recommended that OPT veneers to be grouped prior to
fabrication using systems which is similar to timber stress grading machine (provided that it is
economically feasible) whereby sensors can be used to determine the specific density (SG)
of veneers and mark them accordingly before fabrication. With this system, there will be no
overlapping of SG values between S and I veneers and thus reduce the SG variation within
the same LOPVL quality group.


This study was part of MOSTI ScienceFund project 03-03-10-SF0011 Suitability of Laminated
Oil Palm Veneer Lumber (LOPVL) as Raw Material for Timber based Products. We would to
thank Kin Heng Timber Industry, our industrial partner in this project for lending their LOPVL
board making facilities to us.


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