Question

Which one of the following fibres is mass coloured?

• A. Cotton
• B. Polypropylene
• C. Silk
• D. Wool

Hint:

Polypropylene is almost always mass colored (solution dyed) because it's very difficult to dye after fiber formation due to its hydrophobic nature.

Answer 1

The Correct Option is B

Step 1: Understanding Mass Coloration (Solution Dyeing): Mass coloration, also known as solution dyeing or dope dyeing, is a process where pigments are added to the polymer before fiber formation (either to the molten polymer in melt spinning or to the polymer solution in dry/wet spinning). This results in fibers that are colored throughout their cross-section, rather than just on the surface.
Step 2: Fiber Types and Dyeing Methods: Cotton, Silk, and Wool: These are natural fibers that are typically dyed after fiber formation using various dyeing methods (e.g., with reactive dyes, acid dyes, etc.). They are not typically mass colored. Polypropylene: Polypropylene is a hydrophobic, non-polar fiber that has very poor affinity for most dyes. It's extremely difficult to dye conventionally after fiber formation. Therefore, mass coloration is the primary method for coloring polypropylene. Pigments are added to the molten polymer before extrusion.