Question

The main objective of drawing of synthetic fibre is to impart the molecular __________ along the fibre axis.

• A. crystallinity
• B. orientation
• C. elongation
• D. randomness

Hint:

Drawing is like combing tangled hair; it aligns the "strands" (molecules) so they can work together to provide strength.

Answer 1

The Correct Option is B

Concept: Synthetic fibers, immediately after being extruded from the spinneret (as-spun fibers), have a largely disorganized internal structure. The long polymer chains are tangled and randomly arranged, resulting in a fiber that is weak and highly extensible. To make these fibers commercially useful, they must undergo a process called Drawing.

Step 1: The Mechanism of Drawing.
Drawing involves stretching the fiber between two sets of rollers. The second set of rollers rotates at a much higher surface speed than the first set. This speed ratio (known as the draw ratio) forces the polymer chains to slide past one another.

Step 2: Achieving Molecular Orientation.
As the chains slide, they align themselves parallel to the fiber axis. This alignment is called molecular orientation. By aligning the molecules, the intermolecular forces (such as Van der Waals forces or hydrogen bonds) can act over a larger surface area, significantly increasing the fiber's tensile strength and decreasing its diameter.