Question

Desizing of a grey cotton fabric having a starch-based size can not be done using \(\underline{\hspace{2cm}}\)

• A. Amylase enzyme
• B. Dilute hydrochloric acid
• C. DMDHEU
• D. Hydrogen peroxide

Hint:

Starch is a polymer. To remove it, you need to break it down (hydrolyze or oxidize it). The common methods are: - Enzymatic: Amylase (most popular). - Acidic: Dilute acids. - Oxidative: Hydrogen peroxide, persulfates. A cross-linking resin like DMDHEU is used for an entirely different purpose (wrinkle-free finishing).

Answer 1

The Correct Option is C

Step 1: Understand desizing. Desizing is the process of removing the sizing agent (in this case, starch) that was applied to the warp yarns before weaving. Starch must be broken down into smaller, water-soluble molecules to be washed away. 
 

Step 2: Evaluate the options as desizing agents for starch. 
- Amylase enzyme: Amylase is an enzyme that specifically catalyzes the hydrolysis of starch into sugars. This is the most common and effective method for starch desizing. 
- Dilute hydrochloric acid (Acid desizing): Strong acids can hydrolyze starch, breaking it down into smaller units. This method is effective but can damage the cotton if not carefully controlled. 
- Hydrogen peroxide (Oxidative desizing): Strong oxidizing agents like hydrogen peroxide can break down the starch molecule. This method is also effective. 
- DMDHEU (Dimethylol Dihydroxy Ethylene Urea): This is a cross-linking agent used in finishing to impart wrinkle resistance to cotton. It has no chemical ability to break down starch and is not used in desizing. 

Conclusion: DMDHEU is a finishing agent, not a desizing agent, and therefore cannot be used to remove starch size.