**1. Introduction**

328 Thermoplastic Elastomers

Yong-Hing, K., J. Reilly, et al. (1980). "Prevention of nerve root adhesions after

Nowadays thermoplastics are widely used in industries; many products used different specifications of the thermoplastics that are adapted to their requirement. The importance of consideration to the environmental protection leads the mankind to thinking about producing environment-friendly material, and also controlling the waste material by recycling or reducing them. In the meantime the natural materials such as cellulose based material are one of the major resources that can be used to replace with many manufactured materials. However, cellulosed based material such as natural fibres, because of their degradability, need protection from any circumferential agents. The protection may require a special condition in order to utilise in soil, due to water absorption, soil organisms, and minerals. Natural fibres are amenable to modifications as they bear hydroxyl groups from cellulose and lignin. In addition coating the fibres with any chemical materials reduce their water absorptions and protect them from any bacteria and fungi attack. The hydroxyl groups may be involved in the hydrogen bonding within the cellulose molecules. This weakness of the natural material and good characteristics of natural fibres is the basis of biocomposites invention.


\*OPEFB : Oil Palm Empty Fruit Bunch

Table 1. Chemical and mechanical properties of some important natural fibres

Application of Thermoplastics in Protection of Natural Fibres 331

OPEFB fibre is obtained after the subtraction of oil seeds from fruit bunch for oil extraction. OPEFB fibre is extracted by the retting process of the EFB. Average yield of OPEFB fibre is about 400 g per bunch. Previous studies report the mechanical properties of OPEFB fibres. Table 2 and Table 3 show the summary of oil palm fibre properties (Jacob et al., 2004;

Thermoplastics as a coating can lead to improving the natural fibre performance in two ways: 1. the thermoplastics cover the fibres and keep the fibres from any fungi or bacteria attacks by decreasing the water absorption and contact of the fibres to the soil and any organism inside it, 2. The physical performance of the fibre such as tensile strength and elongation can be affected by modification and coating with any kind of thermoplastics. Therefore, a method was developed to coat the fibres with the thermoplastics. The solvent was used to prepare soluble thermoplastic since the natural fibres cannot reside in high temperature. Different density of the thermoplastic solution was used to evaluate the coated fibres to reach the best strength and resistance. Two types of the fibre were used as a reinforcement of composites such as soil, first the discrete fibres where it needs to be coated one by one, and second is the sheet fibres that were made by compaction of bulk fibres. The fibre was coated by acrylonitrile butadiene styrene (ABS) solution and the characterisation test results for both single and sheet fibres are

ABS is an important engineering copolymer widely used in industry due to superior mechanical properties, chemical resistance, ease of processing and recyclability (Yang et al., 2004). ABS is a common thermoplastic used to make polymeric wood composites, has good physical properties in comparison with other commodity plastics and is cheap in

ABS is derived from acrylonitrile, butadiene, and styrene. The chemical structure of the ABS is shown in Figure 1. Acrylonitrile is a synthetic monomer produced from propylene and ammonia. Butadiene is a petroleum hydrocarbon obtained from butane. Styrene monomers, derived from coal, are commercially obtained from benzene and ethylene from coal. The advantage of ABS is that this material combines the strength and rigidity of the acrylonitrile and styrene polymers with the toughness of the polybutadiene rubber. The most amazing

comparison with other engineering plastics (Huang & Mo, 2002).

mechanical properties of ABS are resistance and toughness.

C

H

C

C

H

H

*l m n*

C C

H

H

C

H

H H

*Acrylonitrile Butadeine Styrene*

H

Sreekala et al., 2001; Sreekala et al., 1997)

**3. Thermoplastic coat** 

described in the following sections.

**3.1 Acrylonitrile butadiene styrene** 

C

C

C N

H

H

Fig. 1. Chemical structure of ABS

H
