Page 48 - Template Tesis UTM v2.0

the classification of natural fibres based on their origin. Bast and leaf quality fibres are

the most commonly used fibres for composite applications. Examples of bast fibres
include hemp, jute, flax, ramie, and kenaf. Meanwhile, leaf fibres include sisal and

banana leaf fibres. The most notable natural fibre is the flax fibre, which has a higher
modulus and less dense, therefore, it produces a lighter composite with better

mechanical properties. The role of natural fibre as reinforcing agents or filler in
developing natural fibre reinforced polymer composites had gained the attention of

several researchers [15, 21, 33–36].

Thus, natural fibres have been used as reinforcements in both thermoplastics
and thermosets matrices, and it was found that the interface between matrix and fibres

is very crucial due to the compatibility problems between the hydrophilic
lignocellulose of natural fibres with hydrophobic resins, which highly influenced the

mechanical and physical properties of the composites. In order to overcome this

problem, the sizing agents and the mercerisation process have been considered to
modify the fibre surface properties. In this regard, chemical treatments that are

typically used to resolve the poor compatibility between the fibre and the matrix in
previous literatures include Sodium hydroxide (NaOH) [37–40] and silane treatment

[1, 41–43], while soy-based resins can be used as sizing agents for the natural fibres.
Moreover, the selection of correct functional groups such as maleinised hydrophilic

hydroxylated oils can bond and strengthen the interface between the natural fibres and

the matrix [16].

In general, natural plant fibres are cell walls comprising of cellulose, hemi-

celluloses, lignin, pectin, waxes and water-soluble substances with cellulose, hemi-
cellulose and lignin, as the basic components affecting to the physical properties of the

fibres as shown in Figure 2.6. Table 2.5 shows the composition of different cellulose

based natural fibres (cotton, jute, flax, ramie and sisal).

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