**3.2.3 Tensile strength of fibre**

334 Thermoplastic Elastomers

structure of a coated fibre is shown in Figure 3(b). The layer of ABS worked as a surface to protect the fibres from water, degradation and physical damages. The entire fibre appears to

be covered and the surface exhibits a smoother surface than the uncoated fibre.

Fig. 3. SEM micrographs of uncoated (left) and coated (right) OPEFB fibre

Fig. 4. Cross section of uncoated (left) and coated (right) OPEFB fibre

some fibre reinforced composites.

ABS filled some of the lacuna like portion in the fibre.

Figure 4(a) presents the cross section of an uncoated fibre, which exhibits a lacuna-like portion in the middle in comparison with Figure 4(b), the SEM micrograph of the crosssection of a coated fibre. The thickness of the coated layer can be seen in the figure, the structure of portions is indicating the penetration of the ABS into the fibre structure. The

The uncoated fibre surface was found to be rough and had protruding portions and groovelike structures on its surface (Figure 5(a)). The surface of the coated fibre has an uneven structure, as shown in Figure 5(b). This feature of surface depends on the application of the fibres where it can be positive or negative due to less friction existence within the fibres and composites mass. Otherwise, the ABS coating may increase the diameter and the section area of fibres which can affect the contact surface area between fibres and soil particles. The surface area of the fibres is the most effective parameter in increasing the shear strength of The tensile strength test result of the coated OPEFB fibre showed an increase in tensile strength of the fibre in breaking point. The elongation of the fibre in tensile test was increased from 15% to near 20% in coated fibre. The main improvement in coated fibres occurs in Young's modulus. Table 5 shows the tensile properties of coated and uncoated OPEFB fibre.


Table 5. Summary of the tensile test result on coated and uncoated OPEFB fibre

Fig. 6. Stress-strain curve of coated OPEFB fibres on tensile test

Application of Thermoplastics in Protection of Natural Fibres 337

Fig. 8. Sorption curves of uncoated and ABS coated OPEFB fibres

For the first phase of experiments, the ABS solution was prepared in three different percentages of 5, 10 and 15 per cents. The 20% ABS solution was excluded from the experiments since some gel-forming behaviour was observed. The specimens were soaked for one minute in 5%, 10% and 15% of ANS solution and the tensile test conducted for specimens according to ASTM D4595-86 (2001) specifications. The 15% solution was picked for the rest of the experiments because it gives the optimum results. For next stage, the specimens were soaked in 15% ABS solution and repeated the tensile tests to study the effect

OPEFB sheets are commercially available is Malaysia. These sheets are manufactured through a compaction process in which the fibres orient randomly (Figure 9). Sheets are

**3.3 Characterization of coated fibre sheets** 

of soaking duration on tensile strength.

**3.3.1 Fibre sheets** 

The tensile test result showed that the ABS coat was broken before failure of the OPEFB fibre, the gaps in the stress strain curve within the strain of 10% to 15% in Figure 6 describe the weakness of the coated fibres to handle the force. Figure 7 shows the photographs of the coated fibre before and after the tensile test. The split of the ABS coating was shown clearly at different strain of OPEFB fibre and ABS thermoplastic. From the figure the gap in the stress strain curve represented the failure of the ABS coat before the OPEFB fibres. The strain of the ABS thermoplastic (Table 3) also proves this result.

Fig. 7. Coated OPEFB fibre before and after tensile test, a) coated OPEFB fibre, b) Break of the coating after tensile test
