This paper was presented at the 4th International Conference on Production Engineering and Design for Development, PEDD'93, Faculty of Engineering, Ain Shams Univ- Cairo, December 27-29, 1993.
Abstract
As a part of a large program of exploring the possibility of utilizing agricultural residues in Egypt , this study was undertaken to evaluate the basic properties of one layer particleboards from palm leaves midribs, and to compare these properties with those of currently produced flaxboards.
Boards were produced from each of palm leaves midribs particles and flax shivs under the same conditions. Resin content was 8.2/(based on oven dry weight) and press conditions were 150°C, 25 Kg/cm 2 and 11 minutes. Mechanical properties in static bending (MOR and MOE) and internal bond strength as well as dimensional stability properties were determined.
The results showed that particleboards of adequate strength and stability can be produced from palm leaves midribs. Palmboards were statistically equal in stiffness (MOE) and internal bond strength to flaxboards. However, palmboards was lower in MOR than flaxboards.
Thickness swelling of palmboards was higher than flaxboard. Water absorption after 2-hour soak was higher in palmboards but it was lower after 24-hour soak than flaxboards. Linear expansion, also was higher than flaxboard after 2-hour soak but statistically equal to flaxboards after 24-hour soak.
In the light of increasing demands for an inexpensive panel products in Egypt and based on the result of this study, palm leaves midribs is suitable for producing medium density particleboard. However, further investigation into the optimum conditions of particle geometry, adhesion and pressing condition of palm leaves midribs are needed to improve the board quality.
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Introduction
Particleboard industry has been established in Egypt in response to the need for an inexpensive panel products. It utilizes wood furnish mainly from casuarina and eucalypt wood and by products of other industries such as flax shivs and bagasse as its raw material. Limited supply of this material coupled with the growing future demanded for particleboard, requires the search for additional raw material supply. Combining wood furnishes with agricultural residues is a very active research field. Using agricultural residues will increase the value of such materials. In addition, these material almost have a lower density and as a general rule the lover density of raw material is preferred in particleboard manufacture.
Flax shivs as a raw material has been used for particleboard manufacture in the early of 1960's. The mechanical properties as well as dimensional stability properties of flaxboard were very good in comparing with other type of particleboard in Egypt (EL-Osta et al 1988). They indicated in another study in 1991 that mixing of flax shivs with casuarina particles modified the casuarina particieboard properties. They attributed their results to mixing lower density raw material with high density of wood furnish.
Date palm leaves midribs are available as a secondary product from annual pruning of palms with a rate of 0.5 million ton yearly in Egypt (EL-Mousely 1992). Previous work demonstrated the suitability of date palm leaves for the manufacture of pulp and paper (Human 1935, AL-Zubaidy et al 1978; Bukhaev and Sarkies 1975; and Sabarwal et al 1978).
In Egypt the Center for Development of Small-Scale Industries and Local Technologies, Faculty of Engineering, Ain- Shams University has begun a part of large program of exploring the possibility of utilizing date palm leaves midribs (DPLM) as a raw material for particleboard manufacture. The objective of this study, therefore is to evaluate the properties of particieboard made of date palm leaves midribs and comparing these properties with flaxboard properties manufactured under the same conditions.
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Material and Methods
Board Manufacture
3-layer boards were constructed at EL-Nasser Company for Production of Particleboard and Resins, EL-Mansoura from palm leaves midribs and flax shivs. The raw material was produced by using Pallmann Double Stream Mill. The boards were nominally 122 by 244 Cm by 1.6 Cm in size. The screen analysis of palm leaves midribs and flax shivs were as follow :
Palm leaves midribs Flax shivs
Fraction % Fraction %
Course 15-30 Course 15-20
Half-course 50-70 Half-course 60-80
Fine 15-35 Fine 10-15
The construction variables were as follow :
1. Binder; Commercial urea-formaldehyde, 60 percent resin solid content.
2. Resin content: 8.2 percent (based on ovendry weight of particles).
3. Catalyst: 6 percent ammonium chloride.
4. Mat moisture content: 10 percent.
5. Pressing conditions:
5.1. Press temperature: 150°C.
5.2. Press time: 11 minutes including two minutes closure time.
5.3. Pressure: 25 Kg/Cm 2 .
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Preparation of Specimens and. Testing
After manufacturing the boards as described in the preceding section, four unsanded boards were selected from each of palm boards and flaxboard. The boards were conditioned to equilibrium at 20°C and 65 percent relative humidity (RH).
Specimens representing both type of particleboard were prepared from each board for determining average modulus of elasticity (MOE), modulus of rupture (MOR), internal bond (IB) strength, specific gravity, moisture content and dimensional stability properties. The mechanical properties test specimens were conditioned at 20°C and 65 RH prior to testing. All tests were conducted in accordance to ASTM D 1037-89 (1989), except that the static bending specimens had a span of 30 Cm and width of 5 Cm.
The dimensional stability tests consisted of measuring total thickness swelling, water absorption and linear expansion from equilibrium condition to the water soak condition after 2 and 24 hour soaking in water. Specimens were weighted to the nearest 0.01 g. Ail dimensions were measured to the nearest 0*05 mm at the center of each specimen.
Results and Discussion
The averages of strength and dimensional stability properties of particleboard made from each of flax shivs and palm particles are presented in Table (1) . The comparison between the properties of the two types are shown in figure 1. In addition, statistical analysis using t-test for the properties of particleboard process from palm leaves midribs and flax shivs are presented in Table 2.
The result of strength properties (Table 1) indicated that MOR of flaxboard (125 Kg/cm 2 ) was higher than obtained for palmboard (106 Kg/cm 2 ). HOE of flaxboard was lower (17831 Kg/cm 2 ) than obtained for palmboard (18513 Kg/cm 2 ). However, there is no significant differences between stiffness (MOE) in the two species of particieboard. Infernal bond (IB) strength of flaxboard (4.1 Kg/cm 2 ) statistically equal to that obtained for palmboards (4.3 Kg/cm 2 ).
The lower MOR value of palroboards is probably due to the higher raw material specific gravity and particle geometry (Vital et al 1974, Shuler and Kelly 1976 and Gertjejansen et al 1978).
The result of dimensional stability properties indicated that thickness swelling after 2 and 24 hour soaking in water of palmboards (22.2 and 25.3 t, respectively) were higher than obtained for flaxboards (12.7 and 19.1 t, respectively). Water absorption after 2 hour soak was higher for palroboards (78 %) than obtained for flaxboards (64.9 %). However, water absorption after 24-hour soak, flaxboards (104.8 %) was statistically higher than palmboard (89.6 %) as shown in Table 2 and Fig 1. Regarding to the linear expansion after the 2-hour soaking, paimboards (0.217 %) was higher than that obtained for flaxboard (0.107 %). However there is no significant difference between the two board species in linear expansion after 24-hour soak . The greater thickness swelling recorded by boards from palm leaves midribs would be attributed to the larger internal voids in the boards because of their large particle size (Gertjejansen et al 1978).
In the light of increasing demands for an inexpensive panel products in Egypt and based on the result of this study, palm leaves midribs is suitable for producing medium density particleboard. However, further investigation into the optimum conditions of particle geometry, adhesion and pressing condition of palm leaves midribs are needed to improve the board quality.
Table (1) Average of Strength and Dimensional Stability Properties of Particleboard made of palm particles and flax shives
No. : Number of test specimens.
LSD 0.05 : Least significant difference at 0.5 percent level of probability.
- Means with the same letter are not significantly different.
- Values in parentheses represent the standard deviation.
Table (2) Analysis of Variance for Properties of ParticIeboard Made of Palm Leaves Midrib Particles and Flax Shivs
* Significant at 95 percent level of probability.
** Significant at 99 percent level of probability.
N.S Not significant.
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Fig. 1. Mean Values of Strength Properties, Dimenensional Stability after 2-hour Soak. and Dimensional Stability after 24-hour Soak of Particleboard made of Palm Leaves Midribs and Flax Shives.
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References
American Society for Testing and Materials. 1989. Standard methods of evaluating the properties of wood-base fiber and particle panel materials. ASTM D 1037-89 Philadelphia , Pa. USA .
AL-Zubaidy. A.S.; V.Th. Bukhaev and M.L.AL-Douri (1978): Date palm fiber: A possible new use, Trop. Sci.20 (I): 59p.
Bunkhaev. V. Th. and T.Sarkies (1975): Determination of the pentosan and potential furfurai in different parts of date palm and obtaining furfurai and furfuramide from these parts. Palm and Dates Research Center Technical Bulletin No.3, 17 pp, Baghdad : Palm and Dates Research Center (En, with Ar summ.).
EL-Mousely, H. 1992. Annual report for using date palm leaves midribs in composite board manufacture. Center for Development of Smali-Scale Industries and Local Technologies. Faculty of Engineering, Ain-Shams University .
El-Osta, M.L.M.; M.M.Megahed, and M.M.El-Morshedy. 1988. Properties of particleboard from windbreak trees. Alex. J.Agric.Res. 16(4); 46-59.
El-Osta, M.L.M.; M.M.Megahed, and M.M.El-Morshedy. 1991. Properties of particleboard from casuarina wood and flax shives mixtures. Alex. J.Agric.Res. 36(3): 155-170. This paper was presented at International Symposium on Particleboard/ Composite Materials March 30, 1993. Seattle , Washington , USA .
Gertjejansen, R.O.; D.W. Haavik, S.P.A. Okoro, H.F. Carino, and H.J. Hall. 1978. Properties of particleboards from mixture of Philippine hardwoods. Forest Prod. J. 28 (12): 21-27
Shuler, C.E. and R.A. Kelly. 1976. Effect of flake geometry on mechanical properties of eastern spruce flaketype partiecleboard. Forest Prod. J. 26 (6): 24-28.
Vital, B.R.; W.F. Lehmann and R.S. Boone. 1974. How species and board densities affect properties of exotic hardwood particleboards. Forest Prod. J. 24 (12): 37-45.
Zahdy and Sayer. Palm and dates research Center Technical Bulletin No.6, llpp. Baghdad : palm and Dates Research Center (En/ with Ar, summ).
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