**6.1 Density of composite board from compressed oil palm fronds**

Density is an excellent indicator of the amount of substance in a piece of wood [40]. The density of the composite board from compressed oil palm fronds will depend on the maturity groups, portions, and types of the resin that have been used for bonding this composite board. **Table 2** shows the mean value results for the density of the composite board for each maturity group, portion, and resin type. **Table 2**, showed that the highest density for this composite board came was from


#### **Table 2.**

*Value for density of the composite board.*

the bottom portion for each maturity group followed by the middle and then top portions. The matured maturity group possessed the highest density values for every portion of the intermediate and young maturity groups.

According to the obtained results in **Table 2**, the decreased summarised composite board from compressed oil palm fronds density from the bottom to top portions for each maturity group and from the old to young maturity groups for each portion was influenced by internal structure in the oil palm fronds by its abundance of vascular bundles and parenchymatous tissues. The analysis of variance (ANOVA) in **Table 7** indicates the significant difference between density with maturity groups and portions. Nevertheless, no significant difference was indicated between the utilization of resin to produce composite boards. Hence, the density value of the composite board did not affect the types of resin.

Nonetheless, the compactness of the compressed oil palm fronds higher than the raw oil palm fronds density by the effect of resin penetration used in producing this composite board. It was found that the presence of both resins could increase the density of the composite board from compressed oil palm fronds that cause the increase in a material substance per unit volume in this composite board.

### **6.2 Basic density of composite board from compressed oil palm fronds**

**Table 3** indicates the mean values of basic density for the composite panel from compressed oil palm fronds for each maturity group, portion, and resin types. Decreases in values of the basic density from the bottom to the top portion for each maturity group and from the old to young maturity groups for each portion were caused by the high concentration of fibrous vascular bundles of the oil palm composite boards [55, 56]. The basic density differs according to their cell size, cell wall thickness, and relative amount of solid cell wall material. Mature and thickly cells occurred at the bottom part of the wood resulting in higher basic density values than other parts. The decreases in the basic density value from the fronds' bottom portion to the top is due to the growing differences in the anatomical cell maturity development [57]. Both density and basic density are the main factors affecting the strength properties of wood.

The analysis of variance (ANOVA) in **Table 7** indicates the significant difference between density with maturity groups and portions. Nevertheless, no significant

**Maturity Groups Basic Density (g/cm<sup>3</sup> ) at different Portions Bottom Middle Top** Matured Phenol Formaldehyde Composite Board 0.38 0.36 0.33 Urea Formaldehyde Composite Board 0.39 0.35 0.32 Intermediate Phenol Formaldehyde Composite Board 0.36 0.35 0.32 Urea Formaldehyde Composite Board 0.37 0.34 0.31 Young Phenol Formaldehyde Composite Board 0.34 0.33 0.30 Urea Formaldehyde Composite Board 0.34 0.32 0.30 *Source: Rasat et al. [54].*

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

#### **Table 3.**

*The basic density of the composite board.*

difference was indicated between the utilization of resin to produce composite boards. Hence, the density value of the composite boards did not affect the types of resin. According to Paridah and Anis [58], the parenchyma acts similar to a sponge and easily absorbed moisture. On that account, this composite could effortlessly absorb phenol and urea-formaldehyde resin during the production process and increasing the basic density of the composite board of compressed oil palm fronds.
