123
5
5.1.3 Aramid Fibres
Aramid fibres have a peculiar morphology and distinct low surface
energies. The salient features of the morphology of aramid fibres are
the following:
5 Aramid fibre has highly oriented chain structure.
5 It has a skin–core heterogeneity; hence it has a low interfacial
strength.
5 Poor adhesion with most polymers.
The methods to improve fibre/matrix adhesion are the following:
5 Mechanical roughening of the surface.
5 Silane coupling agent used for glass fibre.
5 Isocyanate-linked polymers.
5 Acid or base hydrolysis yields a terminal amino group on the
fibre surface.
5 Bromine water treatment.
5 Plasma treatment in vacuum, ammonia, or argon.
The properties of the composite materials are determined by those
of the raw materials, shape of the filler, morphology of the system,
and nature of the interphase between the phases. The properties of
composites are altered by a change in morphology or interphase.
An important property of the interphase that can greatly affect
mechanical behaviour is the strength of the adhesive bond between
the fibre and the matrix [10, 11].
5.2 Physical Forms of Reinforcements
Mostly, reinforcements are in the form of fabrics. Fabrics are used
in high-end applications where high mechanical properties are
required. Reinforcement in the form of rovings and tows is used for
high-performance applications, such as pressure vessels using filament winding process. The common forms of fabric reinforcements
are given next.
Woven Fabrics Woven fabrics provide continuous reinforcement
to composites, and their weaves and patterns have been discussed
in 7 Chap. 1. Fabrics made out of glass fibres, carbon fibres, graphite fibres, Kevlar fibres, PEEK fibres, UHMWPE fibres, etc. are
available.
Chopped Strand Mat (CSM) CSM has been discussed in detail in
7 Chap. 1. It is commonly made out of glass fibre staples.
Meshes Meshes are made out of both glass and carbon fibres. Their
thickness is usually small (approximately 7–10 μm and 15–20 μm for
carbon fibre meshes and glass fibre meshes, respectively). They are
used for the surface finishing operation during the moulding of composites.
5.2 · Physical Forms of Reinforcements
5
5.1.3 Aramid Fibres
Aramid fibres have a peculiar morphology and distinct low surface
energies. The salient features of the morphology of aramid fibres are
the following:
5 Aramid fibre has highly oriented chain structure.
5 It has a skin–core heterogeneity; hence it has a low interfacial
strength.
5 Poor adhesion with most polymers.
The methods to improve fibre/matrix adhesion are the following:
5 Mechanical roughening of the surface.
5 Silane coupling agent used for glass fibre.
5 Isocyanate-linked polymers.
5 Acid or base hydrolysis yields a terminal amino group on the
fibre surface.
5 Bromine water treatment.
5 Plasma treatment in vacuum, ammonia, or argon.
The properties of the composite materials are determined by those
of the raw materials, shape of the filler, morphology of the system,
and nature of the interphase between the phases. The properties of
composites are altered by a change in morphology or interphase.
An important property of the interphase that can greatly affect
mechanical behaviour is the strength of the adhesive bond between
the fibre and the matrix [10, 11].
5.2 Physical Forms of Reinforcements
Mostly, reinforcements are in the form of fabrics. Fabrics are used
in high-end applications where high mechanical properties are
required. Reinforcement in the form of rovings and tows is used for
high-performance applications, such as pressure vessels using filament winding process. The common forms of fabric reinforcements
are given next.
Woven Fabrics Woven fabrics provide continuous reinforcement
to composites, and their weaves and patterns have been discussed
in 7 Chap. 1. Fabrics made out of glass fibres, carbon fibres, graphite fibres, Kevlar fibres, PEEK fibres, UHMWPE fibres, etc. are
available.
Chopped Strand Mat (CSM) CSM has been discussed in detail in
7 Chap. 1. It is commonly made out of glass fibre staples.
Meshes Meshes are made out of both glass and carbon fibres. Their
thickness is usually small (approximately 7–10 μm and 15–20 μm for
carbon fibre meshes and glass fibre meshes, respectively). They are
used for the surface finishing operation during the moulding of composites.
5.2 · Physical Forms of Reinforcements