Question

Surface modification of Polyester imparts

• A. Smoothness to Polyester
• B. Silky feeling to Polyester
• C. Scroopiness to Polyester
• D. Shining to Polyester

Hint:

• Polyester fibers can be surface modified to improve their aesthetic and comfort properties.
• Alkali weight reduction} is a common surface modification for polyester. It hydrolyzes the fiber surface, making it softer, more pliable, and giving it a silk-like feel and drape}.
• Other surface modifications can target smoothness, moisture management, etc.
• Achieving a "silky feeling" is a key objective of many polyester finishing treatments.

Answer 1

The Correct Option is B

Polyester fibers are synthetic and, in their unmodified state, can sometimes have a somewhat harsh, plastic-like feel, and can lack some of the desirable aesthetic and comfort properties of natural fibers like silk or cotton. Surface modification of polyester fibers or fabrics is done to improve these properties. Common surface modification techniques include:

• Alkali hydrolysis (Caustic reduction / Weight reduction): Treatment with strong alkali (e.g., NaOH) at high temperatures. This partially hydrolyzes the surface of polyester fibers, removing some material from the surface. This process can:
  • Make the fibers finer.
  • Create a softer, more supple handle.
  • Impart a silk-like feel and drape (often called "peach skin" effect if done mildly, or a more drapey, silky effect with more weight reduction).
  • Improve moisture absorption and comfort to some extent.
• Enzyme treatments: Using specific enzymes to modify the surface.
• Plasma treatments: Using gas plasma to alter surface chemistry and topography.
• Application of surface finishes: E.g., silicone softeners, hydrophilic finishes.

The question asks what surface modification of polyester imparts. Given the options are mostly about tactile or visual properties:

• (a) Smoothness to Polyester: Some surface modifications can improve smoothness, e.g., by removing surface irregularities or applying smoothing finishes.
• (b) Silky feeling to Polyester: This is a very common goal of polyester surface modification, especially alkali weight reduction. It aims to mimic the desirable soft, smooth, and drapey feel of silk.
• (c) Scroopiness to Polyester: "Scroop" is a rustling sound and a crisp, firm feel characteristic of some silks (especially wild silks or silk treated in a certain way). While some treatments might aim for specific tactile effects, achieving scroop in polyester is less common as a primary goal than achieving general silkiness.
• (d) Shining to Polyester: Polyester can be inherently lustrous (bright polyester) or delustered (semi-dull, full-dull). Surface modifications like alkali treatment can sometimes enhance luster by smoothing the surface, but "shining" might also refer to the base luster from fiber cross-section and delustrant level, not just surface modification effect. Trilobal cross-section gives shine.

Considering the common objectives and outcomes of polyester surface modification, imparting a "Silky feeling" is a primary aim, particularly through alkali weight reduction treatment. This makes the fabric softer, more pliable, and more like natural silk in its handle and drape. The image shows only option (b) having text and being marked correct. \[ \boxed{\text{Silky feeling to Polyester}} \]