COC Materials Science & Technology 1 — Questions and Answers
Question 1: Which property describes a material's ability to return to its original shape after deformation without permanent change?
- Elasticity (Correct answer)
- Plasticity
- Viscoelasticity
- Ductility
Correct answer: Elasticity
Elasticity is the material property that allows a substance to fully recover its original dimensions upon removal of the applied load.
Question 2: Carbon fiber composite materials used in O&P are reinforced with carbon fibers primarily to improve which mechanical property?
- Stiffness-to-weight ratio (Correct answer)
- Impact resistance
- Thermal conductivity
- Chemical resistance
Correct answer: Stiffness-to-weight ratio
Carbon fiber composites have an exceptionally high stiffness-to-weight ratio, making them ideal for energy-storing prosthetic feet and lightweight orthotic shells.
Question 3: Thermoplastic materials used for custom orthotics are typically formed at temperatures between:
- 150–180°F (65–82°C) (Correct answer)
- 300–350°F (149–177°C)
- 400–450°F (204–232°C)
- 500–550°F (260–288°C)
Correct answer: 150–180°F (65–82°C)
Low-temperature thermoplastics commonly used for splints and orthotics soften and become moldable at 150–180°F, allowing direct patient molding.
Question 4: What is the primary advantage of using titanium over steel in prosthetic structural components?
- Higher strength-to-weight ratio (Correct answer)
- Lower cost
- Greater flexibility
- Better corrosion resistance only
Correct answer: Higher strength-to-weight ratio
Titanium offers a superior strength-to-weight ratio compared to steel, allowing structurally sound prosthetic components at significantly reduced mass.
Question 5: Viscoelastic materials exhibit which combination of properties?
- Both viscous (time-dependent) and elastic (recoverable) behavior (Correct answer)
- Only elastic deformation under all loads
- Permanent deformation under any stress
- Constant stiffness regardless of loading rate
Correct answer: Both viscous (time-dependent) and elastic (recoverable) behavior
Viscoelastic materials exhibit rate-dependent behavior, combining elastic recovery with viscous energy dissipation, as seen in gel liners and dynamic foot keel materials.
Question 6: Which type of polypropylene is most commonly used for thermoplastic AFO fabrication?
- Copolymer polypropylene (Correct answer)
- Homopolymer polypropylene
- High-density polyethylene
- Acrylic resin
Correct answer: Copolymer polypropylene
Copolymer polypropylene is preferred for AFOs because it offers better impact resistance and flexibility at thin sections compared to homopolymer.
COC Materials Science & Technology 1
Which property describes a material's ability to return to its original shape after deformation without permanent change?