Which of the following is NOT a purpose of the matrix phase in fiber-reinforced composites?

• A. Protect the dispersed fiber phase
• B. Lock in the position of the fiber phase
• C. Disperse forces to the fiber/dispersed phase
• D. Conduct heat between the fiber and dispersed phase

Answer: (D)

The matrix phase in a fiber-reinforced composite serves to bind and surround the fibers, hold their positions, and transfer applied loads to the fibers through the fiber–matrix interface. It also protects the fibers from environmental and mechanical damage and provides ductility and toughness to the material. Heat conduction between the fiber and dispersed phase isn’t a defining role of the matrix; thermal transfer in a composite depends more on the conductivities of both phases and the quality of the interface rather than being a primary purpose of the matrix itself. So the statement about conducting heat between phases is not a fundamental purpose of the matrix.