Matrix is the continuous phase in a composite and it binds the reinforcement together to form different shapes. The matrix plays a minor role in the load-bearing capacity of the composite, since it simply transfers the load to the reinforcements. However, the matrix has a major inuence on the interlaminar and in-plane shear properties. The interlaminar shear strength is an important design consideration for the composite structures under bending loads, whereas the in-plane shear strength is important under torsional loads. Poor interlaminar shear strength may lead to the separation of layers and poor in-plane shear strength may lead to the debonding of bers from the matrix. The matrix provides lateral support against ber buckling under compressive loading and thus inuences the compressive properties of the composites also. To some extent the processability and defects in a composite material depend strongly on the characteristic properties of the matrix, such as viscosity, melting point, and curing temperature (in the case of thermoset polymer matrix).