Question

What are the factors affecting the air permeability of fabric?
A. weave
B. yarn twist
C. yarn strength
D. cover factor Choose the correct answer from the options given below:

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

Hint:

Air permeability is all about "holes." If a factor (like weave or cover factor) changes the size or number of holes in the fabric, it will affect air permeability.

Answer 1

The Correct Option is B

Concept: Air permeability refers to the rate of airflow through a known area of fabric under a specific pressure differential. It is a critical property for clothing comfort, filters, and parachutes, primarily determined by the "open area" or porosity of the fabric structure.

Step 1: Analyzing Structural and Yarn Factors.

• A (Weave): The interlacing pattern directly affects the number and size of pores in the fabric. For instance, a plain weave is generally less permeable than a loose hopsack or twill weave because it has more interlacing points that pull the structure together.
• B (Yarn twist): Increasing yarn twist makes the yarn more compact and circular, which can increase the space between yarns in a fabric, thus affecting permeability.
• D (Cover factor): This is the most dominant factor. A higher cover factor means the yarns are packed more tightly, reducing the available air gaps and significantly lowering air permeability.

Step 2: Exclusion.
C (Yarn strength) is a mechanical property related to the force required to break the yarn. While strength is important for durability, it does not physically block or facilitate the passage of air through the fabric pores.