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 molecular weight of a single repeat unit

Answer

The ratio of crystalline to amorphous content

Answer

The number of crosslinks per unit volume

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

Epoxy

Answer

Polyester resin

Answer

Phenolic resin

Question 3

In polymer science, creep refers to:

Accepted Answer

Time-dependent deformation under sustained stress below the yield point

Answer

Immediate elastic deformation upon loading

Answer

Rapid crack propagation through a polymer

Answer

The return of strain after stress removal

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

Prevent delamination of plies

Answer

Keep fiber volume fraction below 60%

Answer

Prevent fiber buckling under compression

Question 5

Delamination in laminated composite structures most commonly initiates at:

Accepted Answer

Free edges and ply drop-offs due to interlaminar stresses

Answer

Fiber-matrix interfaces within plies

Answer

The center of the laminate under bending

Answer

Sites of fiber waviness

Question 6

Which composite manufacturing process uses vacuum pressure to infuse resin into a dry fiber preform?

Accepted Answer

Vacuum-assisted resin transfer molding (VARTM)

Answer

Filament winding

Answer

Autoclave prepreg layup

Answer

Pultrusion