Drill

1
Drill

• How are natural fibers different from synthetic
  fibers?
• What is the most common types of natural fibers?

2
Fiber Analysis
3
Chapter 4 A Study of Fibers and Textiles

• identify and describe common weave patterns of
  textile samples
• compare and contrast various types of fibers
  through physical and chemical analysis
• describe principle characteristics used to
  identify common fibers
• apply forensic science techniques to analyze
  fibers

4
Natural Fibers

• ______________ are the plant fibers most
  ______________ used in textile materials.
• Type of cotton, _________ and degree of _________
  contributes to the diversity of these fibers.
• Processing techniques and color applications also
  influence the value of cotton fiber
  identification.

5
Natural Fibers

• Other plant fibers used in the production of
  textile materials include ______, _____ and
  _____.
• The animal fiber most frequently used is
  ________, typically from sheep.
• ____________ of fiber determined by usage in
  final fabric application.

6
Fiber Classification Natural Fibers

• _________ fibers (made of proteins)
• Wool from ______, cashmere and mohair from
  ______, angora from ______, and hair from
  alpacas, llamas, and camels are commonly used in
  textiles.
• Shimmering silk from caterpillar _________ is
  longer and not as easily shed.

7
Fiber Classification Natural Fibers

• Plant fibers (made of the polymer cellulose)
• can ________ water.
• are __________ in water.
• are very ___________ to damage from harsh
  chemicals.
• can only be _________ by strong ______.
• can be ___________ at crime scenes because they
  become ________ over time.

8
Fiber Classification Natural Fibers

• Plant fibers
• Cotton from _________ is the plant fiber most
  commonly used in textiles (shown above).
• _______ from ________ is durable.
• Hemp, jute, and flax from stems grow in bundles.
• __________ and sisal from leaves deteriorate more
  quickly.
• Mineral Fibers
• __________ is a fibrous form of glass.
• __________ is a naturally occurring mineral with
  a crystalline structure.

9
Fiber Classification Synthetic (artificially
produced) Fibers

• Until the nineteenth century only plant and
  animal fibers were used to make clothes and
  textiles.
• __________ the products produced today are
  artificially produced.
• Artificially produced fibers include ______,
  ________, _________, _________, and ____________.
  

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Blue Cotton (denim)
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Orange Cotton
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Flax and Wool
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Fiber Classification Synthetic (artificially
produced) Fibers

• Regenerated Fibers (derived from cellulose)
• __________ is the most common of this type of
  fiber. It can imitate natural fibers, but it is
  __________.
• __________is cellulose chemically combined with
  __________ and is often found in carpets.
• ____________ nylon is cellulose combined with
  three acetate units, is breathable, lightweight,
  and used in performance clothing.

14
Fiber Classification Synthetic (artificially
produced) Fibers

• Synthetic Polymer Fibers
• ___________ is the basis for these fibers, and
  they have very different characteristics from
  other fibers.
• ____________ in large vats are joined together
  to form polymers. The fibers produced are spun
  together into yarns.
• They have no ____________ structures, and under
  magnification they show regular diameters.

15
Fiber ClassificationSynthetic (artificially
produced) Fibers

• Examples of synthetic polymer fibers spandex
  nylon
• _________found in polar fleece,
  wrinkle-resistant, and not easily broken down by
  light or concentrated acid added to natural
  fibers for strength.
• __________easily broken down by light and
  concentrated acid otherwise similar to
  polyester.
• ___________inexpensive, tends to ball easily,
  and used as an artificial wool or fur.
• ___________high performance, quick drying, and
  resistant to wear.

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Green Polyester
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Red Polyester
18
Man-made Fibers

• The shape of a ___________ fiber can determine
  the value placed on that fiber.
• Cross section of a man-made fiber can be
  manufacturer-__________.
• Some ___________ are more common than others, and
  some shapes may only be produced for a ________
  of time.

19
Man-made Fibers
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Comparison of Natural and Synthetic Fibers

• Visual Diagnostics of Some Common Textile Fibers
• under Magnification

21
Yarns, fabrics, and textiles

• Fibers can be twisted (spun) into ______ of any
  length, thick or thin, loose, or tight. A blend
  can be made to meet different needs such as
  resistance to __________.
• Fibers can be woven into ________ or ________.
• Threads are arranged side by side (the _______).
• More threads (the _____) then are woven back and
  forth crosswise in one of a number of different
  patterns through the warp.

22
Yarns, fabrics, and textiles
Weave Patterns
23
Man-made Fibers

• More than ______ of all fibers used in textile
  manufacturing are man-made.
• ___________ and ________ fibers are the most
  _________encountered man-made fibers, followed by
  __________, _________ and __________.

24
Sampling and Testing

• Weaving spun fibers (yarns) together produces
  clothing and many textiles.
• ___________ from an article of clothing or a
  textile is the most _________ form of fiber
  transfer.
• Natural fibers require only an _______ microscope
  to find characteristic _______ and _________.
• ___________________ can reveal something of the
  chemical structure of other fibers that,
  otherwise, may look very much alike.

25
Sampling and Testing

• If a large quantity of fibers is found, some can
  be subjected to ________ tests such as burning
  them in a flame (see analysis key above) or
  ___________ them in various liquids.
• Crimes can be solved in this way by ___________
  fibers found on different suspects with those
  found at the crime scene.

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. . . . . . . . . . . . . . . . . Summary

• Fibers are spun into yarns having specific
  characteristics.
• Yarns are woven, with different patterns, into
  clothing or textiles.
• Fibers, trace evidence, are a form of class
  evidence used by crime scene investigators.
• Fiber evidence may be gathered using different
  techniques.
• Fibers may be analyzed using burn tests, tests
  for solubility in different solutions, polarized
  light microscopy, or infrared spectroscopy.