Fiber Characteristics – Comprehensive Notes (Pizzuto’s Fabric Science 12th Ed.)

Fiber Characteristics – Comprehensive Study Notes

  • Overview and purpose

    • Understanding terminology to express and communicate textile fiber properties.
    • How fiber selection and fiber properties affect fabric usage and finished product performance.
    • Recognize natural and manufactured fiber sources.
    • The chapter uses the Fiber Characteristics section of the Fabric Science Swatch Kit (Swatches 1–15 cover various fibers).

  • Key terminology (glossary of related terms)

    • Abrasion resistance, absorbency, cover, crimp, dry spinning, elasticity, epitropic fibers, fibrillation, filament fibers, flameproof fibers, flame-resistant fibers, flammability, flammable fibers, flexibility, hand, hydrophilic, hydrophobic, hygroscopic, luster, manufactured fibers, melt spinning, natural fiber, pilling, resiliency, specific gravity, spinnerette, staple fibers, static electricity, strength, thermoplastic, tow, wet spinning, wicking.

  • Fiber sources: natural vs manufactured

    • Natural fibers: obtained from plants or animals. Plant sources include stems (e.g., flax, hemp, jute, ramie), leaves (e.g., sisal, abaca), seeds (e.g., cotton). Animal fibers include wool, cashmere, mohair, vicuña; silk is an animal fiber (from silkworm cocoon, not mammalian fur).
    • Manufactured (man-made) fibers: designed to resolve specific problems/needs via chemical solutions forced through spinnerettes to form filaments. They can be used as filaments or cut into staple lengths and may be crimped/textured.
    • Both natural and manufactured fibers have identifiable assets/drawbacks depending on end use.

  • Fiber origins in context

    • Natural fibers come from plants/animals; examples: cotton (seed hair), flax (stem), hemp (stem), jute (stem), ramie (stem), sisal (leaf), abaca (leaf), wool (animal), cashmere/mohair (animal), vicuña (animal), silk (silkworm cocoon).
    • Manufactured fibers are created from chemical solutions; common examples include nylon, polyester, acrylic, acetate, spandex, etc.

  • Spinnerette and filament formation (manufactured fibers)

    • Spinnerette: device used to form filaments; may be as small as a thimble or as large as a plate with tiny holes.
    • Filaments are initially produced as continuous filaments; may be kept as filaments or converted to staple fibers.
    • Hole shape and size affect the cross-sectional shape of the fiber; larger/more holes yield different filament yarns.
    • The number of holes, hole shape, and hole size are chosen according to the desired filament fiber/yarn; small spinnerettes for filament yarns; large for high production tow.
    • Materials used to make spinnerettes include platinum and stainless steel; hole shapes can produce round, triangular, “T,” etc., cross-sections.
    • Filament formation methods (common):
    • Dry spinning: solvent is evaporated in warm air to solidify the filament.
      • Examples: acetate, modacrylic.
    • Wet spinning: filament solution is spun into a liquid coagulation bath to harden into filaments.
      • Examples: acrylic, viscose rayon.
    • Melt spinning: solid polymer is melted and extruded into cool air to solidify.
      • Examples: glass (not a textile fiber in common clothing), nylon, polyester, olefin.

  • Fiber structure and its performance linkage

    • A fiber’s structure influences the performance characteristics of the fabric and finished products.
    • Key determinants of structure: physical attributes, chemical composition, and molecular arrangement.
    • Fiber structure affects strength, abrasion resistance, resiliency, and other properties; also determines feel and appearance of fabrics.

  • Physical attributes of fibers

    • Length: shapes fiber form.
    • Shape: cross-section and overall longitudinal shape influence luster, bulk, and hand.
    • Surface: smooth, rough, grooved, deeply channeled, or wrinkled; influences hand, luster, wicking.
    • Longitudinal configuration: straight, twisted, coiled, or crimped; crimp affects bulk, warmth, and comfort.
    • Diameter: thickness affects stiffness, wrinkle resistance, bulk, drape, and softness.

  • Fiber length vs filament and staple concept

    • Filament fibers: long continuous length; silk is naturally filamentous; many manufactured fibers start as filaments.
    • Staple fibers: short lengths (e.g., 1/2 inch to 36 inches natural variations). Most natural fibers (cotton, flax, wool) and some manufactured fibers are produced as staple fibers.
    • Silk is the only natural fiber typically found as filament; others vary in length.
    • Practical example lengths (typical ranges):
    • Silk: about 1,600 yards (1,463 m) long, can be cut to shorter lengths.
    • Cotton: usually 1/2 inch to 2 1/2 inches (1.27 cm to 6.35 cm).
    • Flax: usually 2 inches to 36 inches (5.08 cm to 91.44 cm).
    • Wool: usually 1 inch to 18 inches (2.54 cm to 45.72 cm).
    • Some fibers (natural rubber, metallic) can be filamentary but are not naturally filamentous.

  • Fiber cross-sectional shapes and light interaction

    • Cross-section shapes influence bulk, texture, luster, and hand.
    • Light reflection varies with cross-section:
    • Flat-surfaced fibers have more luster than round fibers.
    • Round fibers reflect light in a single general direction, producing a shiny surface.
    • Multilobal fibers scatter light, producing a diffuse glow with glitter (bright spots at lobe tips).
    • Irregular cross-sections scatter light in many directions, yielding duller appearances and fewer highlights; scattering can mask soiling (e.g., carpeting) and lower color saturation.
    • Photomicrographs illustrate various cross-sectional shapes and surface textures (Figures 2.2 and 2.3 in the text).

  • Fiber surfaces and texture

    • Surfaces vary from smooth to rough, grooved to wrinkled.
    • Wool is scaly; cotton is smooth; rayon can be serrated.
    • Surface characteristics affect hand, luster, and wicking (see Chapter 3 for more on hand and related properties).
    • Photomicrographs (Figure 2.5) show examples of surface textures across fibers.

  • Fiber longitudinal configuration and crimp

    • Longitudinal configuration describes whether fibers are straight, twisted, coiled, or crimped.
    • Cotton fiber is naturally twisted; nylon fiber tends to be straight.
    • Crimp definition: bends and twists along the fiber length.
    • Effects of crimp:
    • Increases resiliency, bulk, warmth, elongation, absorbency, and skin comfort.
    • Decreases hand softness and luster as crimp increases.
    • Crimp helps a fiber stand off the skin to reduce clinging and can create a cooled sensation when worn.
    • Crimp improves the fiber’s ability to withstand repeated bending without breaking.
    • Tow and texturing:
    • Tow is a thick rope of thousands of filaments; can be heat-set to maintain crimp configuration.
    • Texturing is a process used to add crimp to filaments after yarn production.
    • Crimp can also be observed in yarns when fabric construction causes interlacing/interlooping effects.

  • Fiber diameter and its implications

    • Diameter relates to stiffness: thicker fibers are stiffer and more wrinkle-resistant; may feel rougher.
    • Large-diameter fibers yield bulkier fabrics due to poorer packing; thin fibers produce sheer, lightweight, drapable fabrics.
    • Natural fibers have varying diameters along their length; manufactured fibers are more uniform in diameter along their length and can be produced across a wide diameter range.

  • Chemical composition and molecular formation

    • Fibers are classified by chemical composition into groups:
    • Cellulosic (e.g., cotton, flax) – natural fiber group.
    • Protein (e.g., wool, silk) – natural fiber group.
    • Synthetic (e.g., polyester, nylon, acrylic) – manufactured fibers.
    • Even within a category, fibers can have different properties.
    • Chemical composition determines:
    • Reactions to bleaches, sunlight, moths, mildew, flames, and perspiration.
    • Whether the fiber is thermoplastic (can be melted) and how it dyes.
    • Molecular arrangement influences strength, abrasion resistance, and resiliency.
    • For natural fibers, modification is limited; for manufactured fibers, modifications are possible within chemical structure constraints, enabling many variations via technology.
    • Concept: reverse engineering – identify the optimum fundamental fiber properties for a given fabric and then design the structure (yarns, fabric, finishes) to achieve those ends.

  • Fiber-performance properties (Table 2.1 categorization)

    • Four primary categories of fiber-performance properties:
    • Aesthetics: visual and tactile effects.
    • Durability: resistance to signs of wear.
    • Comfort: physical comfort and wearability.
    • Safety: danger or risk of injury (e.g., flammability).
    • Example properties within each category:
    • Aesthetics: Flexibility, Hand, Luster, Cover, Pilling.
    • Durability: Abrasion resistance, Strength, Resiliency, Specific gravity (density impact on performance).
    • Comfort: Absorbency, Elasticity, Wicking, Thermoplasticity, Environmental sensitivity.
    • Safety: Flammability, Chemical effects, Static electricity.
    • Note: Some properties span multiple categories (e.g., cover relates to aesthetics and practical warmth; elasticity affects comfort and fit; thermoplasticity affects care and shaping).

  • Aesthetic properties in detail

    • Flexibility: Ability to bend easily and repeatedly without breaking.
    • Examples: acetate yields drapable fabrics; glass yields stiff fabrics; fiber thinness improves drapability.
    • Trade-offs: more rigid fabrics suit shapes like peplums or rigid backpacks.
    • Hand: The feel of fiber/yarn/fabric when handled; influenced by fiber shape, surface, and configuration; affected by yarn type, fabric construction, and finishing processes; descriptors include soft, crisp, dry, silky, stiff, harsh.
    • Luster: Light reflected from a surface; influenced by surface smoothness, crimp, cross-section, and fiber length.
    • Smoother surfaces, less crimp, flatter cross-sections, and longer fibers increase luster.
    • Delusterants (e.g., titanium dioxide) reduce luster to create dull or semidull appearances; delustering is used to achieve matte effects in fabrics like matte nylon or polyester.
    • Finishes, yarn type, weave, and finishing processes also alter luster.
    • Cover: The ability to occupy area; thicker fibers or fibers with crimp/curl provide better cover; fewer fibers needed for warmth and substance.
    • Wool’s crimp creates air-filled spaces that improve insulation and cover.
    • Cross-sectional shape, longitudinal configuration, and weight affect covering power.
    • Pilling: Formation of small fibers or fiber ends that form tiny balls on the surface due to wear; undesirable for aesthetics and comfort; more common on hydrophobic fibers due to static attraction and surface behavior; wool can pill because of its scaly surface; stronger fibers tend to hold pills more; weak fibers may shed pills.
    • Hydrophobic vs Hydrophilic tendencies influence pilling, static buildup, and comfort.
    • Hydrophobic fibers tend to pill more, due to static attraction and less internal moisture to dissipate charges; hydrophilic fibers resist static buildup better but may pill less or shed pills more readily depending on fiber and surface.
    • Hydrophobic fibers (e.g., polyester, nylon) may show less friction-induced wear in some cases but can pill more due to surface interactions; silk and wool are hygroscopic/hydrophilic to some degree but pill under wear due to surface characteristics.
    • Scales and surface texture (e.g., wool) contribute to tailored hand and appearance.

  • Durability properties in detail

    • Abrasion resistance: Ability to resist wear from rubbing; critical for durability in outerwear and daily-use fabrics; high breaking strength and abrasion resistance improve long-term wear (e.g., nylon is strong and abrasion resistant; acetate has poor abrasion resistance and may fray or wear in linings).
    • Strength (Tenacity): Fiber’s ability to withstand stress; measured as breaking force per unit weight, expressed in
    • units: grams per denier (g/denier) or newtons per tex; the term breaks into a consistent concept of breaking force relative to fiber mass.
    • Note: Glass, nylon, and polyester are typically strong; acetate and acrylic are weaker; durability arises from fiber chemistry and structure as well as fabric construction.

  • Comfort properties in detail

    • Absorbency: Ability to take up moisture; usually expressed as moisture regain percentage; regaining moisture from the air under standard conditions (e.g., 70°F/21°C and 65% RH).
    • Hydrophilic fibers readily absorb water; natural animal/vegetable fibers are hydrophilic; rayon, lyocell, and acetate are hydrophilic among some manufactured fibers.
    • Hydrophobic fibers absorb little water.
    • Absorbency affects skin comfort, static buildup, dimensional stability in water, stain removal, water repellency, and wrinkle recovery.
    • Higher absorbency improves wetness comfort but can increase wrinkling and dimensional changes when washed.
    • Hygroscopic: Fibers that absorb moisture without feeling damp (e.g., silk and wool).
    • Dimensional stability in water: Hydrophobic fibers generally shrink less when washed than hydrophilic fibers; swelling of fibers in water influences dimensional stability.
    • Stain removal: Hydrophilic fibers are typically easier to wash out stains because water and detergent penetrate more readily.
    • Wicking: The ability to transfer moisture along a fiber or fabric surface; high in some hydrophilic fibers and certain microdenier olefins; smooth surfaces reduce wicking; wicking is advantageous in performance/athletic fabrics; transported moisture to the fabric surface where it evaporates.
    • Elasticity: The ability to elongate under tension and recover to original length; important for comfort, fit, and seam stress reduction; elastomeric fibers (e.g., Spandex, Elasterell-p, Lastol, rubber) can extend by at least 100% and recover closely to original length.
    • Specific gravity (density): Ratio of fiber mass to an equal volume of water (at a standard temperature, ~4°C). Lightweight fibers provide warmth without heavy weight; this influences bulk and insulation (e.g., acrylic is lightweight but warm).
    • Static electricity: Frictional electric charge buildup from rubbing two dissimilar materials; effects include cling and lint attraction; moisture reduces static; hydrophobic fibers are more prone to static; epitropic fibers (conductive carbon/metal content) can dissipate static; carpets made with such fibers reduce static issues in homes.
    • Wicking is especially relevant in performance fabrics where moisture is moved away from the skin to evaporate at the surface (e.g., COOLMAX® AIR fibers with propeller-shaped cross-section to move sweat quickly to the surface).

  • Safety properties in detail

    • Flammability: Ability to ignite and burn; textiles are classified as flammable, flame-resistant, or flameproof.
    • Flammable fibers ignite easily and sustain combustion.
    • Flame-resistant fibers have higher ignition temperatures and burn more slowly; may self-extinguish.
    • Flameproof fibers do not burn.
    • Finishes can modify flammability (e.g., regular polyester is flammable; treated polyester can be flame resistant).
    • The “Business of Textiles” notes emphasize the consequences of improper fiber selection (recalls) highlighting real-world safety implications.
    • The concept of elasticity and its business relevance to product fit and ease of use is tied to consumer expectations and design capabilities.

  • Economic and practical implications

    • The importance of selecting appropriate fibers to meet end-use requirements; improper selections can lead to recalls and brand cost.
    • Example recalls include rayon skirts in 1994 that were dangerously flammable; yoga pants with nylon/Lycra blend being recalled for being too thin and pilling quickly; silk scarves recalled for flammability concerns.
    • These cases underscore the need for informed professionals with textile-specific expertise; fiber properties must be matched to end-use, care, and safety standards.
    • Elasticity and design considerations affect SKU count and supply chain complexity; fibers with stretch properties enable easier fit and may reduce the need for closures.
    • The “Textile Connection” reinforces the necessity of fiber selection in the product development process.

  • Identification of textile fibers and fiber-testing concepts

    • Because most fibers can look/touch similar, identification relies on several tests with tradeoffs in speed, cost, and accuracy.
    • Burning (combustion) test: a quick, simple method to identify fiber groups (cellulosic vs synthetic) and specific fibers by odor, smoke color, and ash/residue after burning. Finishes can alter burning behavior; blends complicate interpretation.
    • Test procedure for burning:
    • Use a small bundle of yarns (5–6) or a fringe; burn from the free end while holding with tweezers or coins.
    • Use a fireproof surface (aluminum foil) to collect residue; warps/fabrics should be burned separately in each direction if needed.
    • Observe whether the fiber melts, odor, smoke color, residue type, and self-extinguishing behavior to aid identification.
    • Acetone test (Acetate test): Acetate fibers dissolve in acetone; applying acetone quickly dissolves acetate while other fibers remain unaffected; can quantify acetate fraction by weighing swatches before/after treatment.
    • Chlorine bleach test: Silk and wool fibers may yellow and eventually disintegrate under liquid chlorine or household bleach; separation into individual fibers is recommended for maximum exposure.
    • Dry and wet strength test: Compares fiber strength when dry vs when wet; some fibers (e.g., rayon) weaken when wet, others may gain strength; useful for differentiating viscose rayon from cotton/flax after burning tests.
    • Chemical solubility test (Table 2.3): A sequence of solvents used to identify fibers by solubility; multiple fibers in a blend may dissolve in different solvents; the sequence eliminates options progressively.

  • Practical testing considerations and safety

    • Many tests involve hazardous chemicals; use gloves, aprons, goggles, and proper ventilation.
    • Solvent handling requires caution; acetone is highly flammable.
    • Proper lab environment and handling are critical when performing fiber identification tests.

  • Table and figure references (context from the chapter)

    • Table 2.1: Categories of fiber-performance properties (Aesthetics, Durability, Comfort, Safety) with associated properties (Flexibility, Hand, Cover, Luster, Pilling, Abrasion resistance, Strength, Wicking, etc.).
    • Table 2.2: Burning characteristics of textile fibers by group (cellulosic, protein, manufactured); general burning behavior and odor expectations.
    • Table 2.3: Chemical solubility test results (solvents and which fibers dissolve) – used in a sequential testing approach.
    • Figures 2.1–2.8: Various depictions of spinnerette cross-sections, cross-sectional shapes, surface textures, light reflection from cross-sections, photomicrographs of fibers, and the burning test setup (e.g., Fig. 2.8).
    • Notable example: COOLMAX® AIR fibers illustrating engineered moisture transport via a propeller-shaped geometry to speed moisture movement to the surface for evaporation.

  • Worked examples and study prompts (selected as representative review material)

    • Study questions touch on identifying properties and selecting appropriate fibers for specific uses, understanding the effects of fiber crimp on end-use performance, and differentiating fibers via burning tests and solvent tests.
    • Example prompts:
    • State the fiber property that most affects a given condition (e.g., pilling propensity, permanent pleats, insulation, wear resistance, static buildup, hand, drapability, etc.).
    • Explain how to adjust spinnerette design to produce thicker filament fibers, more filaments, or a different cross-sectional shape.
    • Compare two identical fibers with different cross-sections (round vs triangular) in terms of appearance and hand.
    • Explain why cotton is produced mostly as staple fibers while polyester can be produced as both filament and staple.
    • Define crimp and explain its effect on fabric properties.
    • Discuss how fiber absorbency influences fabric performance.
    • Describe what causes pilling and why it varies by fiber type.
    • Decide which fiber would be better for performance wear based on wicking vs absorbency.
    • Identify everyday scenarios where static buildup is common.
    • Define covering power and its importance in blanket production with manufactured fibers.

  • Swatch Kit and assignment notes

    • Fabric Science / Swatch Kit Assignment 2.1 involves defining and identifying characteristics with swatch references (Cover, Flexibility, Hand, Luster, Resiliency, etc.).
    • The assignment requires selecting samples that illustrate strong/poor cover, drapability, harsh/soft hand, lustrous/dull appearance, and good/poor resiliency.

  • Additional practical takeaways

    • The fiber selection process is a core driver of end-use performance, cost, and consumer satisfaction.
    • Accurate fiber identification and testing informs product development, quality control, and compliance with safety standards.
    • Understanding thermoplasticity helps in process design (dyeing, heat-setting, embossing) and care labeling.
    • The interplay of fiber properties with yarn structure, weave/knit fabric construction, and finishing determines the final performance of textiles in real-world use.

  • Quick reference formulas (LaTeX)

    • Tenacity (conceptual):
      extTenacity=extBreakingforceextLinearmassdensityext{Tenacity} = \frac{ ext{Breaking force}}{ ext{Linear mass density}}
    • Moisture regain (definition):
      extMoistureregain=m<em>extwet−m</em>extdrymextdryimes100%ext{Moisture regain} = \frac{m<em>{ ext{wet}} - m</em>{ ext{dry}}}{m_{ ext{dry}}} imes 100\%
    • Specific gravity (relative density):
      SG = rac{
      ho{ ext{fiber}}}{ ho{ ext{water}}} ext{ (at standard conditions, ~4°C)}
    • Absorbency concept (moisture uptake):
      ext{Absorbency}
      ightarrow ext{percentage of moisture regain under standard conditions}

  • Key takeaways for exam prep

    • Be able to distinguish natural vs manufactured fibers, and give examples of each with their typical properties and end-uses.
    • Understand how cross-section, surface texture, and crimp influence luster, hand, cover, and warmth.
    • Recognize how chemical composition governs fiber behaviors under heat, chemical exposure, and care (dyeing, finishing, bleaching).
    • Memorize the four categories of fiber-performance properties and representative properties within each category.
    • Know at least the general testing approaches for identifying fibers (burning test, acetone test, chlorine bleach test, dry/wet strength), plus the sequence logic of solvent solubility testing.
    • Appreciate real-world implications of fiber choice, including historic recalls and current industry practices that emphasize safety, performance, and consumer satisfaction.

  • End of notes