**3.2.1 FTIR**

The chemical reactions during fibre coating were characterised using IR spectroscopy. IR spectra of the uncoated and coated OPEFB fibres are given in Figure 2 (Bateni et al., 2011). Series (a) is the IR spectra for ABS, Series (b) shows the IR spectra of OPEFB fibre and series (c) and (d) show the coated OPEFB fibre infrared spectra, for coating incubation times of 6 hour and 24 hour, respectively. ABS coating imparts physical and chemical modifications to the fibre. A band shown in the 3300–3600 cm−1 regions in coated and uncoated OPEFB fibre corresponds to O–H stretching of the cellulose and lignin. The intensity of the 1636 cm-1 band increased and the 3400 cm-1 band was shifted to 3420 cm-1, corresponding to C=O stretching and O–H stretching vibrations after coating of the fibre, respectively. Strong peaks are observed in the IR spectrum of coated fibres at 2239 and 2929 cm-1 when compared with the uncoated fibre. Peak detected at 1455 cm-1 may correspond to the characteristic peaks of ABS plastic which are the aliphatic C–H stretching (Sreekala et al., 2000).

The presence of a peak at 2929 cm−1 may be due to C–H stretching. The peaks at 1039 and 2929 cm-1 for coated fibres were increased and shifted, corresponding to C–O stretching and C–H stretching vibrations. The change C=C peak frequency increased with coating. Two peaks were observed at approximately 2347 cm−1 due to C≡N stretching. The shifting of the 2347 cm-1 band to 2239 cm-1 indicates the change in C≡N stretching of the OPEFB fibre after coating by ABS. Those peaks which changed over the time show the increment the presence rate of ABS in coated fibres. The presence of the peaks over the time increment shows that

The chemical resistance for ABS is relatively good and it is not affected by water, non organic salts, acids and basic. The material will dissolve in aldehyde, ketone, ester and some chlorinated hydrocarbons. The properties of moulded ABS are shown in Table 4 based on

An ABS solution was prepared by adding ABS pieces to methyl ethyl ketone (MEK) solvent. Fibres were chopped into 30 mm length for water absorption tests and 100 mm length for tensile strength tests. The average aspect ratio for 100 mm length fibre was found to be equal to 250. The chopped OPEFB fibres were incubated in the 15% ABS solution to be coated.

The chemical reactions during fibre coating were characterised using IR spectroscopy. IR spectra of the uncoated and coated OPEFB fibres are given in Figure 2 (Bateni et al., 2011). Series (a) is the IR spectra for ABS, Series (b) shows the IR spectra of OPEFB fibre and series (c) and (d) show the coated OPEFB fibre infrared spectra, for coating incubation times of 6 hour and 24 hour, respectively. ABS coating imparts physical and chemical modifications to the fibre. A band shown in the 3300–3600 cm−1 regions in coated and uncoated OPEFB fibre corresponds to O–H stretching of the cellulose and lignin. The intensity of the 1636 cm-1 band increased and the 3400 cm-1 band was shifted to 3420 cm-1, corresponding to C=O stretching and O–H stretching vibrations after coating of the fibre, respectively. Strong peaks are observed in the IR spectrum of coated fibres at 2239 and 2929 cm-1 when compared with the uncoated fibre. Peak detected at 1455 cm-1 may correspond to the characteristic peaks of ABS plastic which are the aliphatic C–H

The presence of a peak at 2929 cm−1 may be due to C–H stretching. The peaks at 1039 and 2929 cm-1 for coated fibres were increased and shifted, corresponding to C–O stretching and C–H stretching vibrations. The change C=C peak frequency increased with coating. Two peaks were observed at approximately 2347 cm−1 due to C≡N stretching. The shifting of the 2347 cm-1 band to 2239 cm-1 indicates the change in C≡N stretching of the OPEFB fibre after coating by ABS. Those peaks which changed over the time show the increment the presence rate of ABS in coated fibres. The presence of the peaks over the time increment shows that

Property Test Method Value Tensile Strength ASTM D638 44.8 MPa Flexural Modulus ASTM D638 2.59 GPa Tensile Elongation ASTM D638 15 % Flexural Yield Strength ASTM D790 69 MPa Flexural Modulus ASTM D790 2.59 GPa

MatWeb (2009) material specification data sheet.

Table 4. Physical properties of moulded ABS

Coated fibres were dried over a mesh at room temperature.

**3.2 Characterization of coated fibres** 

stretching (Sreekala et al., 2000).

**3.2.1 FTIR** 

the chemical reactions of ABS and fibres have increases. This increase led to a more physical stability of ABS coating over fibres and thus fibres were more resistant.

Wave number (cm-1)

### **3.2.2 Fibre surface topology**

The porous surface morphology was useful for better mechanical interlock of fibre with the ABS coating. The SEM micrograph of fibres and the coated fibres clearly shows the surface structure of an uncoated OPEFB fibre and the quality of thermoplastic coat (Figure 3). The micrographs show porous and grooves on the surface of the fibre. The uniform cover and fully coating of the fibre surface is an important factor in protecting the fibres while surface

Application of Thermoplastics in Protection of Natural Fibres 335

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

OPEFB fibre 283 15.4 5500 Coated OPEFB fibre 306 19.1 6600

Elongation at Break (%)

Young's modulus (MPa)

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. 5. Surface structure of uncoated (left) and coated (right) OPEFB fibre

(MPa)

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

**3.2.3 Tensile strength of fibre** 

Type of the fibres Tensile Strength

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

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

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

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 some fibre reinforced composites.

Fig. 5. Surface structure of uncoated (left) and coated (right) OPEFB fibre
