Polymers And Fiber Materials

Step 1: What is a wool blend mark?
The Woolmark Company provides certification marks to guarantee the composition and quality of wool fabrics. One such mark is the Wool Blend Mark, used for blends of virgin wool with other fibers.
Step 2: Minimum percentage requirement.
For a fabric to qualify for the Wool Blend Mark, it must contain at least 60% virgin wool blended with only one other fiber. This ensures wool remains the dominant component in the blend.
Step 3: Why not the other options?
- (0%): Invalid, as wool must be present in majority.
- (10% or 20%): Too low to ensure wool quality or dominance.
- (60%): Correct, as per international standards for wool blends.
Step 4: Importance of wool percentage.
Maintaining at least 60% virgin wool ensures durability, warmth, elasticity, and comfort associated with wool, while still allowing blending for cost reduction or performance enhancement.
Step 5: Conclusion.
Hence, the Wool Blend Mark requires a minimum of 60% virgin wool in the blend.

Step 1: Types of dyeing stages.
- Fiber/Stock dyeing: Dyeing fibers before spinning (e.g., heather effects).
- Yarn dyeing: Dyeing yarns before weaving/knitting (e.g., checks, stripes).
- Piece dyeing: Dyeing fabric after weaving/knitting, most common method.
- Garment dyeing: Dyeing completed garments.
Step 2: Understanding given processes.
- Jig dyeing: Fabric is passed through dye liquor in open width form.
- Beam dyeing: Fabric is wound on a beam and dyed under pressure.
- Winch dyeing: Fabric is circulated in dye liquor using winch rollers.
- Pad dyeing: Fabric is passed through dye bath and squeezed (padded).
- Jet dyeing: Fabric circulates in a rope form with the help of high-pressure jets.
Step 3: Identifying the stage.
All these methods handle fabric (not yarn or fiber) and are categorized as piece dyeing methods.
Step 4: Conclusion.
Therefore, all listed processes belong to Piece dyeing at the fabric stage.

Step 1: Cellulosics.
Cotton and other cellulosics have affinity for reactive dyes due to hydroxyl groups. But the given key pairs them with Basic Dyes (historical use, though not ideal in modern practice).
Step 2: Protein fibers.
Wool and silk are protein fibers. They can take up acid dyes or sulphur dyes depending on treatment. In this match, B → III (Sulphur dyes).
Step 3: Acrylic fibers.
Acrylics have affinity for basic dyes due to the presence of acrylonitrile groups. Hence C → II.
Step 4: Polyester.
Polyester is dyed with disperse dyes due to its hydrophobic nature. Hence D → IV.
Step 5: Conclusion.
Correct matching is A - I, B - III, C - II, D - IV.

Step 1: First step – dissolution.
The dye molecules must first dissolve in water to be available for dyeing. Hence A is the starting step.
Step 2: Second step – dispersion.
Once dissolved, the dye molecules are dispersed uniformly in the dye bath. Hence C follows next.
Step 3: Third step – absorption.
The fiber surface absorbs the dye molecules from the dye bath. Hence B comes after dispersion.
Step 4: Final step – diffusion.
The dye molecules then diffuse into the fiber interior, giving permanent coloration. Hence D is last.
Step 5: Conclusion.
The correct sequence is A → C → B → D.

Step 1: Understanding drapability.
Drapability is the ability of a fabric to fall into graceful folds. Fibers with fine, smooth, and flexible structure have higher drapability.
Step 2: Ranking fibers.
- Silk has the highest drapability due to its smooth filament structure.
- Wool has good drapability because of its crimp and elasticity.
- Cotton has moderate drapability.
- Flax (linen) is stiff, giving the lowest drapability.
Step 3: Conclusion.
The order from high to low is D (Silk) → C (Wool) → A (Cotton) → B (Flax).

Step 1: Source of linen.
Linen is derived from the stalks of the flax plant (Linum usitatissimum). It is one of the oldest fibers used by humans.
Step 2: Elimination of options.
- Jute: Produces coarse fiber used in bags and mats, not linen.
- Cotton: Comes from seed hairs, not stalks.
- Silk: Derived from silkworm cocoons.
Step 3: Characteristics of linen.
Linen fabric is strong, durable, and has high absorbency, making it suitable for summer wear and home textiles.
Step 4: Conclusion.
Thus, linen is the generic name for flax.

Step 1: Purpose of adding TiO\textsubscript{2.}
Synthetic fibers like polyester, nylon, and acrylic are naturally shiny and lustrous.
To reduce this unnatural shine, a delusterant is added. Titanium dioxide (TiO\textsubscript{2}) and geranium oxide are the most commonly used delusterants.
Step 2: Role of delusterants.
These oxides create minute particles within the fiber structure which scatter light.
This reduces brightness and gives the fiber a more natural, cotton-like dull appearance.
Step 3: Option analysis.
- (A) Delusterant: Correct, TiO\textsubscript{2} and geranium oxide are delusterants.
- (B) Moderant: Wrong, this term is not used in fiber production.
- (C) Chelating Agent: Wrong, these are used to bind metal ions in water treatment.
- (D) Oxidising Agent: Wrong, no oxidation role here.
Step 4: Conclusion.
Hence, Titanium oxide and geranium oxide act as delusterants in fiber spinning.

Step 1: Understanding fiber solubility tests.
Different fibers dissolve in specific solvents, and these chemical solubility tests are used to identify fiber types in textile laboratories.
Step 2: Reaction of silk.
Silk is a natural protein fiber made of fibroin. It is known to dissolve in concentrated formic acid (85%) at room temperature. This property is used as a quick identification method.
Step 3: Why not the others?
- Acrylic: Dissolves in dimethylformamide (DMF), not formic acid.
- Wool: Another protein fiber but resists formic acid; instead dissolves in chlorine bleach or strong alkali.
- Polyester: A synthetic thermoplastic fiber, insoluble in formic acid; dissolves in phenol or hot chlorinated solvents.
Step 4: Conclusion.
Thus, the fiber dissolving in 85% formic acid at room temperature is Silk.

Step 1: Understanding regenerated fibers.
Regenerated fibers are produced from natural polymers that are chemically treated and reformed into fibers. Examples: Rayon, Acetate, Lyocell (all derived from cellulose).
Step 2: Rayon.
Rayon is regenerated cellulose made by chemically treating natural cellulose and extruding it into fibers. It is a classic regenerated fiber.
Step 3: Acetate.
Acetate is also derived from cellulose, chemically modified by acetic acid. Thus, it is a regenerated fiber.
Step 4: Lyocell.
Lyocell is a modern regenerated fiber, produced by dissolving wood pulp cellulose in amine oxide solvent. It is eco-friendly and falls under regenerated fibers.
Step 5: Nylon.
Nylon, on the other hand, is a fully synthetic polyamide fiber made from petroleum-based chemicals. It is not derived from natural polymers and hence not regenerated.
Step 6: Conclusion.
Among the options, Nylon is not a regenerated fiber.

Step 1: Concept of burn-out printing.
Burn-out printing is a technique where chemicals are applied to the fabric surface in specific designs.
These chemicals selectively destroy certain fibres in the fabric, creating transparent or semi-transparent patterns.
Step 2: Mechanism.
The process is usually done on blended fabrics such as polyester–cotton or viscose–polyester.
The chemical (like acid paste) removes cellulose fibres, leaving behind the other fibre to form a textured pattern.
Step 3: Differentiating from other printing methods.
- Flock print: Uses adhesive and fibres to create raised patterns, not fibre destruction.
- Warp print: Designs are printed on warp yarns before weaving.
- Pigment print: Uses pigment colours to print on fabric surface, not chemical destruction.
Step 4: Conclusion.
Therefore, the technique that destroys fibres to form design patterns is called Burn-out printing.