Question

The outstanding features of polyamide fiber are \(\underline{\hspace{2cm}}\)
A. Good dimensional stability. 
B. High wet modulus. 
C. High resistance to alkali. 
D. Low strength and high elongation.

• A. A, B and D only
• B. A, B and C only
• C. A, B, C and D
• D. B, C and D only"

Hint:

Key properties of Nylon (Polyamide): - Strong and Tough: Excellent tenacity and abrasion resistance. - Good Elasticity. - Good Dimensional Stability (when heat-set). - Good Alkali Resistance, but poor acid resistance.

Answer 1

The Correct Option is B

Step 1: Recall the key properties of polyamide fibers (e.g., Nylon). Nylons are known for their exceptional strength, toughness, and abrasion resistance.

Step 2: Evaluate each stated feature.
- A. Good dimensional stability: Polyamides are thermoplastic and can be heat-set to provide excellent dimensional stability. They don't shrink or stretch easily after being properly heat-set. This is a correct feature.
- B. High wet modulus: Modulus is a measure of stiffness or resistance to extension. Polyamides retain a significant portion of their stiffness when wet compared to fibers like rayon. This is a correct feature.
- C. High resistance to alkali: The amide linkage (-CO-NH-) in polyamides is stable and resistant to attack by alkalis. They can be scoured and washed in alkaline solutions without significant damage. This is a correct feature. (Note: They have poor resistance to strong acids).
- D. Low strength and high elongation: This is incorrect. Polyamides are known for their high strength (tenacity) and controlled elongation. They are among the strongest synthetic fibers.

Step 3: Combine the correct features. The outstanding features are A, B, and C. Feature D is incorrect. Therefore, the correct option is (B).