Page 59 - Template Tesis UTM v2.0

2.8 Matrices

In most engineering composite systems, matrices play vital roles in providing

unique characteristics for the composite. Composites used in certain industries such as

aerospace, is required to have minimum levels of thermal and electrical conductivity
and the designer must rely on the matrix properties. Generally, the functions and

requirements of the matrix are as follows [55];

• Keeping the fibres in place in the structure
• Help to distribute or transfer loads from external forces to the reinforcement.

• Protect the filaments, both in the structure, before and during fabrication

• Control the electrical and chemical properties of the composite
• Carry inter-laminar shear

The matrix is often required in a finished composite as it provides a solid form

which aids its handling during manufacturing. The matrix also controls the infiltration
process that combines the fibres with the matrix as well during shaping and forming

of the composites. In addition, the matrix material provides a vital inelastic response
which reduces the stress concentrations dramatically. Furthermore, the presence of

matrix materials greatly influences the production cost for composites.

2.8.1 Thermoset

Thermoset is a polymeric material which can be formed by applying heat and

pressure. As a result of a chemical reaction, it is permanently cross linked and cannot
be reformed upon further application of heat and pressure [56]. Thermosetting resins

are often liquid at certain stages in their manufacturing process, they are then cured by
heat, catalysts, or other chemical means. The use of thermoset matrix for composite

material properties characterisation has garnered attention from many researchers

[11, 15, 21, 43, 47, 57–68]. Thermoset resins typically used in composites are epoxy,
phenolic, unsaturated polyester, polyimides, polyurethane and silicones. The

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