ME Polymers and Composite Materials 2

Question 1

Degree of polymerization (DP) is defined as:

Accepted Answer

The number of repeat units in a polymer chain

Answer

The degree of polymerization is the number of monomer repeat units in a single polymer chain, related to molecular weight by DP = M_n / m (repeat unit mass).

Question 2

Which of the following is a thermoplastic polymer commonly used in engineering applications for its high impact strength and transparency?

Accepted Answer

Polycarbonate (PC)

Answer

Polycarbonate is a thermoplastic known for high impact resistance, optical clarity, and good thermal stability, widely used in safety glazing and electronic housings.

Question 3

In polymer science, creep refers to:

Accepted Answer

Time-dependent deformation under sustained stress below the yield point

Answer

Creep in polymers is the slow, time-dependent increase in strain under a constant applied stress, driven by viscoelastic flow of polymer chains.

Question 4

The critical fiber length in a fiber composite is the minimum fiber length required to:

Accepted Answer

Allow full load transfer from matrix to fiber so the fiber can reach its tensile strength

Answer

The critical fiber length is the minimum length needed for the shear stress at the fiber-matrix interface to transfer enough load to bring the fiber to its failure stress.

Question 5

Delamination in laminated composite structures most commonly initiates at:

Accepted Answer

Free edges and ply drop-offs due to interlaminar stresses

Answer

Delamination preferentially initiates at free edges, ply terminations, and ply drop-offs where interlaminar normal and shear stresses are highest.

ME - Materials Engineer Practice Test

ME - Materials Engineer Practice Test

ME Polymers and Composite Materials 2