TXA 260

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alexjking
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42386
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TXA 260
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2010-10-20 14:40:46
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advanced textiles
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Exam 1
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  1. Serviceability
    • -Fitness to consumers' needs (aesthetic, comfort, economic...)
    • -Durability (lifetime)
    • -Maintenance (machine washing, dry cleaning, handwashing)
  2. Approaches of textile testing
    • Service testing
    • Lab testing (reliable, accurate; but indirect)
  3. Goals of textile testing
    • -Conformance to specifications set by standards
    • -Quality control
    • -Product improvement
    • -Adherence to government regulations
    • -Forensic testing
  4. Selection criteria
    • -Appearance (color, style, texture...)
    • -Comfort (hand: soft vs hard, smooth vs rough, cool vs warm)
    • -Price
    • -Serviceability
    • -Maintenance
    • -Safety
  5. Specification
    A precise statement of a set of requirements to be satisfied by a material, product, system or service, indicating whenever appropriate, the procedure by means of which it may be determined whether the specified requirements have been met
  6. Eight sections of specifications
    • 1. Scope
    • 2. Referenced documents: standard testing methods
    • 3. Definitions: ASTM D123
    • 4. Uses and significance: voluntary; some requirements can be modified
    • 5. Sampling: at the time to reach the user; number; size and direction of samples
    • 6. Specification requirements: characteristics, requirements and testing methods
    • 7. Testing methods: details for carrying out the tests
    • 8. Indexing term
  7. Reliable test
    Reliability, consistency, reproducibility, dependability
  8. Precision vs accuracy
    the degree of agreement within a set of tested results

    vs

    the degree of agreement between tested results and the true value
  9. Standard Organizations
    • -Individual companies, government organizations and industry associations
    • -National standard-setting organizations like NRMA, AATTCC, ASTM, ANSI
    • -International standard-setting organizations like ISO
  10. AATCC
    American Association of Textile Chemists and Colorists

    national standard-setting organization
  11. ASTM
    American Society for Testing and Materials

    national standard-setting organization
  12. ANSI
    American National Standard Institute

    a voluntary federation of standards-developing and standards-using organizations
  13. ISO
    International Organization for Standardization

    international standard-setting organization
  14. Factors influencing test results
    Observer, equipment, environment (temperature, humidity), material (sampling), data analysis
  15. Observer influencing test results
    Reading scale, subjective evaluation
  16. Errors in observer reading the scale which affects test results
    Parallax error

    Round off
  17. Errors in observer's subjective evaluation which affects test results
    Change in color, pilling, wrinkling, etc.

    Training; multiple reading (>3 ratings)
  18. Errors with equipment which affects test results
    • Maintenance (keep in good condition)
    • Calibration
    • Verification (checking/recalibration)
  19. Errors with environment which affects test results
    Temperature, humidity
  20. Temperature
    equivalent to the amount of energy in the motion of atoms and molecules
  21. Standard temperature for testing:
    • 70 + 2oF (21 + 1oC)
    • oC = (oF - 32) x 5/9
    • oF = 9/5 oC + 32
  22. Humidity
    the amount of vapor present in the air (%)
  23. Relative humidity (RH)
    the amount of vapor in the air at a given temperature, compared to the maximum limit the air can hold at the same temperature
  24. Moisture regain (MR)
    the percentage of water by weight contained in the specimen
  25. standard relative humidity for testing=
    65 + 2%
  26. Conditioning
    the process of acquiring moisture and temperature equilibrium with standard atmospheric conditions
  27. Sampling rules
    Random, no bias

    1. Do not take specimens from selvage edges (4" margin on both sides of fabric)

    2. Do not take specimens for one test that contain the same yarns (warp-wise sample may contain same filling yarns and vice versa)

    3. Mark and cut specimens accurately and on grain (markers should be small and away from critical areas)
  28. Parts of data analysis
    • Presentation of raw data (table and figure)
    • Statistics: mean, variance, standard deviation, coefficient of variance (CV)
  29. Closeness (fabric parameters)
    ratio of the area covered by threads to that of the area of a fabric (density, size, bulkiness of yarns)
  30. Balance (fabric parameters)
    same kind of yarns in both directions, equal number of warps and fillings in a unit area
  31. thread count (fabric parameters)
    number of yarns per inch

    warps x fillings: 78 x 68
  32. Yarn size (fabric parameters) aka yarn number
    numerical expression which defines fineness of a yarn

    linear density = mass / length
  33. Tex (yarn size)
    grams per 1000 meters of yarn

    1 tex = 9 denier
  34. Denier (yarn size)
    grams per 9000 meters of yarn

    9 denier = 1 tex
  35. Yarn twist (fabric parameters)
    twists per inch (strength, pilling, abrasion, luster...)
  36. Fabric weight (fabric parameters)
    weight per unit area (g/mm2, oz/yd2)
  37. Yarn size in direct system
    Yarn size is expressed in the direct system is directly proportional to the linear density of the yarn

    measures mass per unit length (m / l)

    • Tex: weight of 1000 meter of yarn in grams
    • Denier: weight of 9000 meter of yarn in grams
    • American grain count: weight of 120 yards of yarn in grains (1 lb = 7000 grains, 1 grain = 0.0648 grams)
  38. Yarn size in Indirect system
    Yarn size expressed in the Indirect system is inversely proportional to the linear density of the yarn

    measures length per unit mass (l / m)

    • Cotton count: # of 840 yard lengths per pound
    • Worsted count: # of 560 yard lengths per pound
    • Woolen run: # of 1600 yard lengths per pound
    • Linen lea: # of 300 yard lengths per pound
    • Yards per pound: # of 1 yard lengths per pound
    • Metric count: # of 1000 meter lengths per kilogram
  39. Yarn size standards
    ASTM D2260: Standard Tables of Conversion Factors and Equivalent Yarn Numbers Measured in Various Numbering Systems

    ASTM D1059: Standards Specifies a Test Method to Find the Yarn Number Based on Short Yarn Specimens
  40. Yarn Twist
    In spinning, Twist refers to the turns inserted into a yarn to bind its fibers together

    Twist present in the yarn can be expressed in terms of Turns per inch (TPI) or Turns per meter (TPM)
  41. Twist angle (yarn twist)
    Twist angle is defined as the angle between a tangent to the helix formed by the fiber and the yarn axis

    Twist angle determines the hardness of twist, i.e. it tells us whether the yarn is soft twisted or hard twisted

    Only TPI cannot tell whether the yarn is soft twisted or hard twisted

    Twist angle depends on TPI and yarn size (Tex, denier, cotton count, worsted count, etc.)
  42. Twist factor (yarn twist)
    Twist factor or Twist multiplier is proportional to the tangent of twist angle (tan 0) and it represents the hardness of the twist
  43. In a direct system, Twist factor =
    • TPM x √Tex
    • TPM x √Denier
  44. In an indirect system, Twist factor =
    TPI / √Cotton Count
  45. The higher the twist factor...
    the harder the twisted yarn
  46. A test to find the twist direction
    Rotate the right end of a small yarn sample in the clockwise direction.

    If it results in untwisting the yarn then the yarn has Z-twist
  47. Untwist to Break (yarn twist measurement)
    A specimen is untwisted until it breaks.

    It is assumed that when the yarn breaks it has no twist.

    Twist, as turns per unit length, is calculated as the number of turns registered on the counter divided by the specimen length
  48. Twist contraction method (yarn twist measurement)
    A specimen is untwisted and then re-twisted in the opposite direction until it contracts to its original length.

    It is assumed that the same amount of twist has been inserted as was originally present.

    Twist, as turns per unit length, is calculated as half the number of turns registered on the counter divided by the specimen length
  49. Twist to break method (yarn twist measurement)
    Applicable when the earlier two methods fail.

    Two yarn samples are required

    First yarn sample is untwisted and then re-twisted until it breaks

    Second yarn sample is twisted until it breaks

    Twist, as turns per unit length, is calculated as half of the difference in turns registered on the counter for the first and second yarn sample, divided by the specimen length.
  50. ASTM methods for Yarn Twist Measurement
    D1422 Standard Test Method for Twist in Single Spun Yarns by the Untwist-Retwist Method

    D1423 Standard Test Method for Twist in Yarns by Direct-Counting
  51. ASTM Method for yarn diameter
    ASTM D2130

    Covers a procedure for the determination of average yarn diameter using the micro-projector
  52. ASTM method for fabric weight
    ASTM D3776 is a Standard Test Method for calculating Mass Per Unit Area of a Fabric

    Surface Density = Mass / Area
  53. ASTM method for Fabric Thickness
    ASTM Method D1777 covers the measurement of the thickness of most textile materials using a Compressometer
  54. Fabric Thread Count
    Thread count is defined as number of yarns per unit length of the fabric

    Thread count is also sometimes defined as the total number of yarns in one square unit of the fabric
  55. ASTM methods for Fabric Thread Count
    ASTM D3775 is a standard test method for finding thread count of Woven fabrics

    A part of ASTM D3887 method explains the method of fabric count in Knitted fabrics
  56. Flammability
    Characteristics of a material that pertain to its relative ease of ignition and relative ability to sustain combustion
  57. Flame-resistance
    The property of a material whereby flaming combustion is prevented, terminated, or inhibited following application of a flaming or non-flaming source of ignition, with or without subsequent removal of the ignition source
  58. Flame-retardant
    A chemical used to impart flame-resistance
  59. Fiber content affecting flame-resistance
    Cellulosic fibers such as cotton, flax, viscose have low flame resistance rating

    Woolen fabrics usually have high flame resistance rating

    Thermoplastic fibers shrink from the flame adn tend not to ignite
  60. Fabric weight affecting flame-resistance
    the heavier the fabric, the greater the flame resistance rating
  61. Flammability test methods
    ASTM D6545 Standard Method for Flammability of Textiles Used in Children's Sleepwear - Vertical Flammability test

    ASTM D1230 Standard Test Method for Flammability of Apparel Textiles

    ASTM D4151 Standard Test Method for Flammability of Blankets
  62. Fabric classification based on Flame Spread Time
    The time taken by a flame on a burning material to travel a specified distance under specified conditions

    • > 7s: Class I fabric
    • 4-7s: Class II fabric
    • < 4s: Class III fabric
  63. Crease
    desirable residual bending deformation in garments
  64. Wrinkles
    undesirable residual bending deformations in garments
  65. Crease and wrinkle recovery
    the property of fabric which enables it to recover from being folded and from forming undesirable wrinkles
  66. Wrinkle Resistance (resilience)
    ability to absorb energy without permanent deformation
  67. Wrinkle Recovery (resilience)
    The power to recover original shape a size after removal of the strain which caused the deformation
  68. Resilience
    A fiber may possess this quality to spring back to its original state after being wrinkled
  69. Fiber content affect Crease and Wrinkle Recovery
    Cellulosic materials are notoriously susceptible of creasing

    • Decreasing order of crease resistance:
    • Wool--Silk--Acetate--Nylon--Viscose rayon--Cotton--Flax
  70. Fiber length affecting Crease and Wrinkle Recovery
    Very short fibers tend to be displaced easily when yarns are folded therefore retain permanent deformation
  71. Fiber Geometry affecting crease and wrinkle recovery
    Round x-section fibers resist bending and usually recover quickly from light to medium folding stresses

    Nevertheless, they recover slowly if heavy wrinkles are formed
  72. Yarn twist affecting crease and wrinkle recovery
    Low twisted yarns allow fiber displacement thereby showing poor recovery

    Yarns of medium twist provide littler or no opportunity for fiber displacement, so these yarns tend to return to their original position

    High twisted yarns under heavy wrinkles show poor recovery due to stresses and strains that tend to hold the structure
  73. Yarn mobility
    ability to move in the fabric

    Loose structure allows high mobility
  74. Type of weave affecting crease and wrinkle recovery
    Woven fabrics of basket, twill or satin-weave constructions recover more easily from wrinkles (due to higher yarn mobility) than plain-weave fabrics
  75. Thread count affecting crease and wrinkle recovery
    low thread count fabric structures have higher yarn mobility than high thread count fabric structures thus recover more easily from wrinkles
  76. Crease Recovery test method
    AATCC Test Method 66 - Crease Recovery of Woven Fabrics: Recovery Angle Method

    A test specimen is folded and compressed under controlled conditions of time and forced to create a folded wrinkle. The test specimen is then suspended in a test instrument for a controlled recovery period, after which the recovery angle is recorded
  77. Wrinkle Recovery Test Method
    AATCC Test Method 128 - Wrinkle Recovery of Fabrics: Appearance Method

    A test specimen is wrinkled under standard atmospheric conditions in a standard wrinkling device under a predetermined load for a prescribed period of time. The specimen is then reconditioned in the standard atmosphere for textile testing and evaluated for appearance by comparison with 3-dimensional reference standards
  78. Drape
    The way a fabric hangs

    The property which permits a material to orient itself into graceful folds when acted upon by force of gravity

    Fabric stiffness (resistance to bending) is a key factor in study of drape

    Affected by yarns, weave structure and finish
  79. Relationship between Twist Factor and Fabric Stiffness
    Fabric Stiffness is directly proportional to Twist Factor (yarn twist and linear density)

    • In direct system:
    • TPM x √Tex
    • TPM x √Denier

    • In indirect system:
    • Twist Factor = TPI / √Cotton count
  80. Methods to measure Drape (Fabric stiffness)
    BS 5058: Drape Coefficient measuring using Drape-meter

    ASTM D1388: Cantilever test and Heart Loop test
  81. Drape coefficient relating to fabric stiffness
    High Drape Coefficient signifies stiffer fabric
  82. Relationship between overhang length and bending length in Cantilever test
    Higher overhand length in Cantilever test translates to stiffer fabric
  83. Relationship between Heart Loop length and fabric
    Higher length in Heart Loop test translates to limper fabric
  84. Flexural Rigidity
    Measure of stiffness and defined as work per unit width which is required to bend a fabric to unit radius of curvature
  85. Bending modulus
    Measure of stiffness and is independent of the dimensions of the strip tested and may be regarded as the "intrinsic stiffness"

    Used to compare the stiffness of the material in fabrics of different thicknesses
  86. Pilling
    Bunches or balls of tangled fibers which are held to the surface of the fabric

    Fabric surface fault characterized by little fiber balls or pills of entangled fiber clinging to the cloth surface and giving the garment an unsightly appearance
  87. The Pilling Process
    Development of surface fuzz

    Tangling of the fuzz into pills

    Breaking away of pills
  88. Factors affecting pilling
    Fiber, yarn, fabric structure
  89. How fiber can affect Pilling
    Length: Short fibers have more loose ends that easily protrude from yarn structure, causing more pilling (ex: staple vs. filament yarns)

    Surface characteristics: Smooth fibers show less pilling as compared to fibers with rough surfaces (nylon vs. wool)

    Strength: high strength fibers hold pills on fabric surface more firmly, resulting in more visible pilling (Ex: use of special low strength polyester fibers in woolen blends to reduce pilling)
  90. How yarns can affect Pilling
    Twist: highly twisted yarn structures hold fibers more firmly, resulting in less pilling

    Linear Density (tex, denier): yarn with higher linear density and generally coarse yarns pill more
  91. How fabric structure affects Pilling
    Type of weave: plain weave pills less than other basic weave types (ex: twill and satin weave)

    Thread count: high thread count structures are more compact and pill less
  92. ASTM test method for Pilling
    ASTM D3512: Random Tumble Pilling Test
  93. Types of shrinkages
    Relaxation, Consolidation, Felting, Heat or Thermal, Progressive
  94. Growth
    Increase in fabric dimensions
  95. The Shrinkage Theory
    After wetting, filling yarns swell and warp yarns stretch to accommodate them, and warp yarns relax to relieve the stress, bringing the yarns closer together

    Transverse swelling, longitudinal shrinkage
  96. The Dimensional Stability Test
    AATCC 124 and AATCC 135

    Perform regular washing and drying cycles with the fabric specimen and note down the shrinkage after each cycle
  97. Soiling
    Implies "overall" contamination or discoloration of a material
  98. Staining
    Implies a "local" contamination or discoloration of a material
  99. Soiling and Fiber geometry: Fibers with smooth surface, relatively large diameter, made into smooth yarns and firm fabrics...
    tend to resist soiling
  100. Soiling and Fabric Geometry: Fabrics with loose structure...
    tend to permit penetration of soil into the interstices
  101. Soiling and Fabric Geometry: Fibers with irregular cross-sections...
    provide spaces for soil particles to settle in and hinder their removal
  102. Soiling and Fabric Geometry: Loosely twisted yarns that are somewhat coarse...
    are readily penetrated by soil
  103. Soil release finishes: Oily stains
    • Their removal is primarily dependent upon the hydrophobicity of the fibers
    • Wetting finishes helps water to diffuse between the oil/fiber interface, and thus facilitate removal of oil substances
  104. Soil release finishes: Solid soils
    • Their deposition does not depend upon the hydrophobicity of the fibers
    • It depends upon the adhesion of solid particles to the fiber that is caused by Van der Waal's forces and on the contact area between the fiber surface and the particle
    • The contact area between the fiber surface and the particle is influenced by surface, texture, irregularities, fuzziness, weave
    • Removal of solids from fiber surface requires breaking the adhesive bound between fiber and solid, followed by separation of two surfaces by wetting
  105. Roll-up process (6)
    • Wetting (water and surfactant molecules penetration)
    • Breaking up (small sizes)
    • Separation (oil-fabric interface formation)
    • Rolling up
    • Suspension
    • Redeposition
  106. Wetting in the Roll-up process
    • Surfactant: is wetting agent.
    • Lower the surface tension of the water, loosen, surround, and suspend the soil.
    • Surfactants are molecules made up of two parts.
    • They have heads that are hydrophilic (water-loving) and tails that are hydrophobic (water-hating).
  107. Rolling up step in Roll-up process
    As the hydrophobic tail of a surfactant tries to cling to a surface, it forces itself underneath layers of soil, loosening and lifting it from the surface.
  108. Suspension step in Roll-up process
    • As the cleaning solution rolls up bits of dirt and soil, the surfactant’s hydrophobic tails cling to the particles because they’re not water.
    • The soil is held suspended in the cleaning solution by the power of the surfactant, keeping it from settling back on your countertop.
    • Once the surface is clean, you simply wipe and dry.
  109. Repellent finishes
    • These finishes function by coating the fiber surface to increase its surface tension below that of liquids would wet the fiber. This limited wettability would prevent the unwanted liquid from residing on the fiber surface.
    • These finishes are also effective in preventing or minimizing adhesion of particulate matter to fibers.
  110. Stain Removal Test
    AATCC 130: Stain the test specimen with oil. Perform regular washing and drying cycles and record the amount of residual stain on the test specimen using standard staining replicas after each cycle.
  111. Waterproof fabric
    A fabric that is coated or impregnated with fats, waxes, rubber to form a continuous wall against the passage of water.

    Waterproof fabric has low degree of permeability.
  112. Water resistant fabric
    Water resistance is the ability of a fabric to resist wetting and penetration of water.
  113. Water repellent fabric
    Water repellency is the property of fiber, yarn or fabric characterized by its resistance to wetting by water.

    A water repellent fabric is one whose fibers are usually coated with a hydrophobic compound and whose pores are not filled in the course of treatment.

    This type of fabric is quite permeable to air and water vapors.
  114. Basic concept of wetting and water repellency
    • Surface tension: a tendency to minimize surface area of liquid on a solid surface.
    • High surface tension beads up liquid.
    • Water is polar (postively and negatively charged.
    • When solid surface has polar molecules, water can be attracted and spread—wetting

    • Contact angle (θ) : Angle between the solid surface and the tangent of the water surface as it approaches the solid, the angle being measured in water.
    • WR finish improves contact angle to increase surface tension.
  115. Munsell color system
    • In colorimetry, the Munsell color system is a color space that specifies colors based on three color dimensions, hue, value (lightness), and chroma (color purity or colorfulness).
    • It was created by Professor Albert H. Munsell in the first decade of the 20th century
  116. Hue (Munsell color system)
    • Each horizontal circle Munsell divided into five principal hues: Red, Yellow, Green, Blue, and Purple,
    • along with 5 intermediate hues (YR, GY, BG, PB, RP) halfway between adjacent principal hues.
    • These 10 steps are then broken into 40 sub-steps, (2.5, 5, 7.5, 10).
    • Two colors of equal value and chroma, on opposite sides of a hue circle, are complementary colors, and mix additively to the neutral gray of the same value.
    • The diagram below shows 40 evenly-spaced Munsell hues, with complements vertically aligned.
  117. Value (Munsell color system)
    • Value, or lightness, varies vertically along the color solid, from black (value 0) at the bottom, to white (value 10) at the top.
    • Neutral grays lie along the vertical axis between black and white.
  118. Chroma (Munsell color system)
    • Chroma, measured radially from the center of each slice, represents the “purity” of a color, with lower chroma being less pure (more washed out, as in pastels).
    • Note that there is no intrinsic upper limit to chroma.
    • Different areas of the color space have different maximal chroma coordinates.
    • For instance light yellow colors have considerably more potential chroma than light purples, due to the nature of the eye and the physics of color stimuli.
    • This led to a wide range of possible chroma levels—up to the high 30s for some hue-value combinations (though it is difficult or impossible to make physical objects in colors of such high chromas, and they cannot be reproduced on current computer displays).
  119. How is a color fully specified?
    • by listing the three numbers for hue, value, and chroma.
    • For instance, a fairly saturated purple of medium lightness would be 5P 6/10 with 5P meaning the color in the middle of the purple hue band, 6/ meaning medium lightness, and a chroma of 10.
  120. Munsell Book of Color
    • It uses actual swatches or chips of colored materials.
    • Differences among adjacent chips have been made nearly constant visually.
  121. CIE LAB system
    • L-Lightness
    • A-Redness (positive)--Greenness (negative)
    • B-Yellowness (positive)--Blueness (negative)
  122. Colorfastness
    The property of a dye or a print to retain its hue throughout the wear life of a product.
  123. Crocking
    the degree of color transfer from one colored textile material to another by rubbing.

    A standard white cotton fabric is used for all crocking tests
  124. Colorfastness to Perspiration test method
    AATCC 15: Fabric attached to multi-fiber fabric is dipped in the perspiration solution (pH 4.3±2) for 20-30 minutes and then heated in the oven for at least 6 hrs maintained at 38±1o C (100±2o F).
  125. Colorfastness to Washing test method
    AATCC 61: Multi-fiber fabric is used to see how much color is transferred (staining scale) and then the original specimen is compared to an unwashed specimen to see how much color is lost (gray scale).
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