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FIBRES Ref: Kendall Hunt Publishing company. fibres 2 2 Fibres.

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Presentation on theme: "FIBRES Ref: Kendall Hunt Publishing company. fibres 2 2 Fibres."— Presentation transcript:

1 FIBRES Ref: Kendall Hunt Publishing company

2 fibres 2 2 Fibres

3 fibres 3  Fabric is made of fibres  Fibres are made of twisted filaments  Types of fibres and fabric:  Natural—animal, vegetable, or inorganic  Artificial—synthesized or created from altered natural sources Kendall/Hunt Publishing Company3 Fabric

4 fibres 4 Types of fibres Kendall/Hunt Publishing Company4 Synthetic Natural

5 fibres 5 Kendall/Hunt Publishing Company5 Classification Natural fibres are classified according to their origin: Vegetable or cellulose Animal or protein Mineral

6 fibres 6  Cotton—  Rayon—  Cellulose acetate— Kendall/Hunt Publishing Company6 Cellulose Fibres

7 fibres 7 Fibre Comparison Can you describe the difference(s) between the cotton on the left and the rayon on the right? Kendall/Hunt Publishing Company7

8 fibres 8 Protein Fibres  Wool—  Silk— Kendall/Hunt Publishing Company8 vicuñallama alpaca silkworm

9 fibres 9  Asbestos—  Rock wool—  Fiberglass— Kendall/Hunt Publishing Company9 Mineral Fibres

10 fibres 10  Nylon—  Polyester—  Acrylic—  Spandex— Kendall/Hunt Publishing Company10 Synthetic Fibres Made from derivatives of petroleum, coal, and natural gas

11 fibres 11  fabrics are composed of individual threads or yarns  made of fibres and are knitted, woven, bonded, crocheted, felted, knotted, or laminated  most are either woven or knitted  degree of stretch, absorbency, water repellence, softness, and durability are individual qualities Kendall/Hunt Publishing Company11 Fabric Production

12 fibres 12  Yarn—a continuous strand of fibres or filaments that may be twisted together  Warp—lengthwise yarn  Weft—crosswise yarn  Blend—a fabric made up of two or more different types of fibres Kendall/Hunt Publishing Company12 Weave Terminology

13 fibres 13 Kendall/Hunt Publishing Company13 Plain Weave

14 fibres 14  The warp yarn is passed over one to three weft yarns before going under one.  Makes a diagonal weave pattern. Kendall/Hunt Publishing Company14 Twill Weave

15 fibres 15  The yarn interlacing is not uniform  Creates long floats  Interlacing weave passes over four or more yarns Kendall/Hunt Publishing Company15 Satin Weave

16 fibres 16 Knitted Fabric  Knitted fabrics are made by interlocking loops into a specific arrangement.  It may be one continuous thread or a combination.  Either way, the yarn is formed into successive rows of loops and then drawn through another series of loops to make the fabric. Kendall/Hunt Publishing Company16

17 fibres 17  Synthetic fibres are made of  The word polymer means  The repeating units of a polymer are called  By varying the chemical structure of the monomers or by varying the way they are joined together, polymers are created that have different properties  As a result of these differences, they can be distinguished from one another forensically Kendall/Hunt Publishing Company17 Polymers

18 fibres 18 Filament Cross Sections Synthetic fibres are forced out of a nozzle when they are hot, and then they are woven. The holes of the nozzle are not necessarily round; therefore, the fibre filament may have a unique shape in cross section. Kendall/Hunt Publishing Company18 Round 4-lobed Octalobal Irregular Multi-lobed or Serrate Trilobal Dogbone or Dumbbell

19 fibres 19 Microscopic observation  Burning—  Thermal decomposition—  Chemical tests— Kendall/Hunt Publishing Company19 Testing for Identification

20 fibres 20  Density—  Refractive index—  Fluorescence— Kendall/Hunt Publishing Company20 Testing for Identification

21 fibres 21  Components that make up dyes can be separated and matched to an unknown  There are more than 7,000 different dye formulations  Chromatography is used to separate dyes for comparative analysis  The way a fabric accepts a particular dye may also be used to identify and compare samples Kendall/Hunt Publishing Company21 Dyes

22 fibres 22  Bag clothing items individually in paper bags. Make sure that different items are not placed on the same surface before being bagged.  Make tape lifts of exposed skin areas and any inanimate objects.  Removed fibres should be folded into a small sheet of paper and stored in a paper bag. Kendall/Hunt Publishing Company22 Collection of Fibre Evidence

23 fibres 23 For additional information about fibres and other trace evidence, check out truTV’s Crime Library at: Kendall/Hunt Publishing Company23 More about fibres

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