2
1
Composites have existed in nature right from the evolution of life
on Earth. Wood is the finest example of natural composite in which
cellulose is reinforcement and lignin is matrix. The combination of
bones and musculature is another example of a natural composite
where bones are reinforcements and muscles are the matrix.
Similarly, in orthopods, the exoskeletal body is reinforcement, and
interior soft tissues are matrix. By definition, composites are the
materials/structures that have two or more physically distinct constituent phases, and the resultant properties of these materials/
structures are superior to the properties of its constituent phases.
These phases are primarily reinforcement and matrix and are separated by a distinct interphase. Interphase has a different combination of properties from those of constituent phases. In hybrid
composites, different types of reinforcements are used. A composite
material also may be defined as the heterogeneous material that
consists of two or more constituent materials which do not lose
their characteristics. This combination of constituent materials
results in new desirable properties. Normally, the constituents
(reinforcement and matrix) can be physically identified along with
the interface, which also generally controls the properties of the
composites. The constituents can be organic, inorganic, or metallic
in the form of particles, rods, fibres, plates, foams, etc., and they do
not dissolve or merge completely into each other [1, 2].
The essence of science in composites has been understood from
time immemorial since straw- or bamboo-reinforced mud houses
were built for the purpose of dwelling. The first use of composites
dates back to around 3400 B.C. by the ancient Mesopotamians
when they glued wood strips at different angles to create plywood.
Egyptians and Mesopotamian settlers used a mixture of mud and
straw to create strong and durable buildings in fifteenth century
B.C. Straw continued to provide reinforcement to ancient composite products, including pottery and boats. Houses and kilns made
out of straw-reinforced mud also were used by Indians from ancient
times. Harappa and Mohenjo-daro have plenty of evidence of reinforced structures that were none other than composites. The use of
wattle and daub as composite building material has a history of
6000 years. In these composite structures, a woven lattice of wooden
strips called wattle is used as reinforcement, and the matrix is a
combination of wet soil, clay, sand, animal dung, and straw (called
daub). Wattle and daub are still important construction materials in
many parts of the world [3]. For modern engineering applications,
synthetic polymeric matrices (such as epoxy resin, polyester resin,
polyimide resin, nylon, etc.) are used with naturally occurring mineral fillers (such as wollastonite, silica, mica, talc, and calcium carbonate) and synthetic fibres (like glass, carbon, and Kevlar ® ). Any
solid material that can be processed so that it can embed and adherently grip a reinforcing phase (i.e. fibres or fillers) is a potential
matrix material for composites.
This engineering practice of the fabrication of composites using
natural materials got its boost when man-made fibres and matrix
materials were synthesized. The invention of Bakelite in 1895 was
the stepping stone. In the early 1900s, plastics (such as polyvinyl
Chapter 1 · Introduction
1
Composites have existed in nature right from the evolution of life
on Earth. Wood is the finest example of natural composite in which
cellulose is reinforcement and lignin is matrix. The combination of
bones and musculature is another example of a natural composite
where bones are reinforcements and muscles are the matrix.
Similarly, in orthopods, the exoskeletal body is reinforcement, and
interior soft tissues are matrix. By definition, composites are the
materials/structures that have two or more physically distinct constituent phases, and the resultant properties of these materials/
structures are superior to the properties of its constituent phases.
These phases are primarily reinforcement and matrix and are separated by a distinct interphase. Interphase has a different combination of properties from those of constituent phases. In hybrid
composites, different types of reinforcements are used. A composite
material also may be defined as the heterogeneous material that
consists of two or more constituent materials which do not lose
their characteristics. This combination of constituent materials
results in new desirable properties. Normally, the constituents
(reinforcement and matrix) can be physically identified along with
the interface, which also generally controls the properties of the
composites. The constituents can be organic, inorganic, or metallic
in the form of particles, rods, fibres, plates, foams, etc., and they do
not dissolve or merge completely into each other [1, 2].
The essence of science in composites has been understood from
time immemorial since straw- or bamboo-reinforced mud houses
were built for the purpose of dwelling. The first use of composites
dates back to around 3400 B.C. by the ancient Mesopotamians
when they glued wood strips at different angles to create plywood.
Egyptians and Mesopotamian settlers used a mixture of mud and
straw to create strong and durable buildings in fifteenth century
B.C. Straw continued to provide reinforcement to ancient composite products, including pottery and boats. Houses and kilns made
out of straw-reinforced mud also were used by Indians from ancient
times. Harappa and Mohenjo-daro have plenty of evidence of reinforced structures that were none other than composites. The use of
wattle and daub as composite building material has a history of
6000 years. In these composite structures, a woven lattice of wooden
strips called wattle is used as reinforcement, and the matrix is a
combination of wet soil, clay, sand, animal dung, and straw (called
daub). Wattle and daub are still important construction materials in
many parts of the world [3]. For modern engineering applications,
synthetic polymeric matrices (such as epoxy resin, polyester resin,
polyimide resin, nylon, etc.) are used with naturally occurring mineral fillers (such as wollastonite, silica, mica, talc, and calcium carbonate) and synthetic fibres (like glass, carbon, and Kevlar ® ). Any
solid material that can be processed so that it can embed and adherently grip a reinforcing phase (i.e. fibres or fillers) is a potential
matrix material for composites.
This engineering practice of the fabrication of composites using
natural materials got its boost when man-made fibres and matrix
materials were synthesized. The invention of Bakelite in 1895 was
the stepping stone. In the early 1900s, plastics (such as polyvinyl
Chapter 1 · Introduction