Question

The cotton fiber exhibits poor crease recovery due to \(\underline{\hspace{2cm}}\)

• A. Strong lateral linkages
• B. Flexible polymer chain
• C. Weak lateral linkages
• D. Breakage of polymer chains

Hint:

Why Cotton Wrinkles: 1. Cotton's polymer chains are held by weak hydrogen bonds. 2. When creased, these weak bonds break. 3. The chains slip into a new position. 4. New hydrogen bonds form, locking the wrinkle in place. There are no strong "springs" (like the cross-links in wool) to pull it back.

Answer 1

The Correct Option is C

Step 1: Understand crease recovery. Crease recovery (or wrinkle resistance) is the ability of a fiber to return to its original shape after being bent or crushed. Cotton is known for its poor crease recovery; it wrinkles easily.

Step 2: Analyze the molecular structure of cotton. Cotton is composed of cellulose, which consists of long, linear polymer chains. These chains are highly crystalline, meaning they are packed tightly together in an ordered arrangement. The forces holding these chains together are hydrogen bonds.

Step 3: Relate the structure to the property. When cotton is creased (especially in the presence of moisture), the hydrogen bonds between the cellulose chains break. The chains slip past one another into a new, wrinkled position. In this new position, they form new hydrogen bonds, locking the wrinkle in place. Because the hydrogen bonds are relatively weak and there are no strong cross-links (like in wool) to pull the chains back, the fiber does not recover its original shape.

Step 4: Evaluate the options.
- (A) Strong lateral linkages: Incorrect. If cotton had strong cross-links, it would have good crease recovery.
- (B) Flexible polymer chain: The cellulose chain itself is quite rigid due to its ring structure.
- (C) Weak lateral linkages: Correct. The hydrogen bonds are weak enough to break and reform easily, allowing the chains to slip and set into a creased configuration.
- (D) Breakage of polymer chains: This would be permanent fiber damage, not creasing.