**3.4 Oil palm fronds strength properties**

The oil palm trunk strength properties are proportional to the density variation recognized in both vertical and radial directions. The highest bending strength values from the peripheral lower portion, and the top portion of the central core highlighted the most insufficient strength. Variation of the compression strength parallel to grain also follows the same trend as the bending strength [51]. But, for the oil palm fronds, there is no strength testing done in raw material because compared to the oil palm trunk, there are no uses of oil palm fronds in raw material directly like the trunk.

Some studies have been done in manufacturing composite boards from oil palm fronds compared to their strength properties. Laemsak and Okuma [7] mentioned that there seems to be a good possibility for producing binderless boards using steamexploded fibres of oil palm fronds considering the chemical components of oil palm fronds which are rich in hemicelluloses. The strength properties such as modulus of rupture (MOR) and modulus of elasticity (MOE) of the boards increased linearly with increasing board density as the standard hardboard. They reported that the boards made from fibres treated under a steam explosion condition of 25 N/cm2 (steam pressure) and five minutes (digestion period) exhibited the maximum strength.

The compatibility of oil palm frond cement mixtures was tested in the hydration test, with magnesium chloride (MgCl2) as an accelerator at different water and cement ratios [52]. He reported that the optimum weight ratio of cement-wood increased with decreasing wood powder size based on the equal specific surface area ratio of cement/ wood in the hydration test and board manufacturing. The addition of magnesium chloride improved the compatibility of oil palm fronds with cement, enhancing the cement hydration and ultimate board strength properties. The study dealt with the effects of a curing method that uses gaseous and supercritical CO2 to see its impact on the properties of oil palm fronds cement-bonded board manufactured by the conventional cold-press setting method were carried out by Hermawan et al. [53]. The study showed that high-performance cement-bonded boards made from oil palm fronds were successfully manufactured using the CO2 curing method.

### **4. Processing of compressed oil palm fronds**

The oil palm fronds were obtained from the plantation and selected based on decay-free and no defect. The oil palm fronds were taken from the plantation were divided into three groups according to their maturity. They were the old maturity fronds that have been taken from the below of the fronds crown. The intermediate maturity fronds were obtained from the middle of the frond's crown. The third group was the young maturity fronds that have been taken from the above of the frond's crown. The difference between maturity groups is shown in **Figure 13**.

#### **4.1 Compressed oil palm fronds preparation**

**Figure 14** shows the fresh fronds was obtained from the oil palm tree. Leaflets were removed from the fronds, and then each maturity group was divided into three portions: the bottom, middle and top portion shown in **Figure 15**. A disc about 10 cm in the middle was cut from every portion for the physical properties study for the raw of oil palm fronds, and the rest were peeled of their skin and sliced in the longitudinal direction as shown in **Figure 16**. These sliced fronds were then compressed using rollers compressed machine to increase their density before undergoing sun-drying which has been shown in **Figure 17**.

*Processing and Properties of Oil Palm Fronds Composite Boards from* Elaeis guineensis *DOI: http://dx.doi.org/10.5772/intechopen.98222*

#### **Figure 13.**

*Differences between maturities of oil palm fronds.*

#### **Figure 14.** *Fresh oil palm fronds obtain from the oil palm tree.*

**Figure 15.** *Portion division from the oil palm fronds.*
