**7.2 Compression strength of composite board from compressed oil palm fronds**

Compression strength is defined as the maximum stress sustained by compression of a specimen with the specimen having a ratio of length to smallest dimension [64]. In contrast, Ronald and Gjinoli [65] reported that the characteristic of the compression load-deformation curve was similar to those for static bending strength. The compression strength of the composite is strongly dependent on the effectiveness of the matrix in supporting the fibre against buckling [66].

The obtained data was examined using statistical analysis to define the effect of three parameters like static bending strength test, which were based on maturity groups, portions including types of resin to the compression strength of the composite board from compressed oil palm fronds. According to the testing result, the data is presented in **Table 6** which was based on mean value compression strength. From the display result in **Table 6**, the compression strength value of the old maturity group from bottom to top portions was 473.17, 395.93, and 260.22 N/mm2 for the phenol-formaldehyde composite board, while for the urea-formaldehyde composite board, the result was 459.52, 344.60, and 260.00 N/mm<sup>2</sup> respectively. It can be observed that the compression strength was decreased from the bottom


#### **Table 6.**

*The value for compression strength of the composite board.*

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

portion towards to middle and top portions for the old maturity group. Similar decrement distribution data have been done for intermediate and young maturity groups towards the bottom, middle, and top portions.

**Table 6** showed that the trend for each oil palm fronds composite made from matured, intermediate, and young in maturity groups. The result at matured, intermediate, and young maturity groups was at 473.17, 453.67, and 301.46 N/mm<sup>2</sup> for the phenol-formaldehyde composite boards. The result for the ureaformaldehyde composite was at 459.52, 431.88, and 312.94 N/mm2, respectively. It clearly shows the decrement from mature to intermediate and young groups for the bottom portion. The same trends were also observed in the others two portions (the middle and top).

This was due to the differences in vascular bundle abundance and oil palm fronds, affecting the value of density and basic density. The differences between the latter promote the distribution result of compression strength for the maturity groups and portions. The bottom portion scored higher results in compression strength as compared to others portions. **Table 7** tabulated the ANOVA results that indicate the significant difference between compression strength with maturity groups and portions. According to Oyagade AND Fasulu [67] and Nordahlia [68], some wood properties, including compression strength failure, typically occur in the low density of the wood.

The results obtained showed that the phenol-formaldehyde composite boards possessed higher values than the strength of the urea-formaldehyde composite. This can be attributed to the fact that properly cured phenol-formaldehyde composite resin is usually tougher than the bonded [69]. However, the differences in the compression strengths are not significant as shown in **Table 7**. Therefore, we can conclude that either resin's use does not matter as long as it is economically feasible to produce the mass quantity of the oil palm frond composite boards.


*\*\*indicates citation of the researcher who conducted and produced the data/results.*

#### **Table 7.**

*ANOVA on physical and strength properties of composite board.*
