Question

The crystallinity percentage of silk is

• A. Higher than cotton but lower than wool
• B. Higher than wool
• C. Lower than cotton but higher than wool
• D. Lower than cotton and wool

Hint:

Think of the general trend: Natural protein fibers (wool, silk) tend to have lower crystallinity than natural cellulosic fibers (cotton, linen). Silk is intermediate. Higher crystallinity generally correlates with higher strength and lower extensibility.

Answer 1

The Correct Option is A

Step 1: Understanding Crystallinity: Crystallinity in fibers refers to the degree of structural order. Highly crystalline regions have polymer chains packed closely and regularly, leading to higher strength and stiffness. Amorphous regions have chains arranged randomly, contributing to flexibility and extensibility.
Step 2: Comparing Crystallinity: Wool: Wool has a relatively low crystallinity (around 25-35%) due to its complex, coiled protein structure. This contributes to its elasticity. Cotton: Cotton has a high crystallinity (around 65-70%) due to the highly ordered arrangement of cellulose chains. This contributes to its strength. Silk: Silk has a crystallinity that is intermediate between cotton and wool, around 30-65%. The crystalline regions (beta-sheets) give silk its strength, while the amorphous regions provide some flexibility.
Step 3: The Correct Answer: Thus, the crystallinity of silk is higher than wool and could be as high as cotton, but on average it will be slightly lower.