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Chapter Fifteen – Textile Fibers

Chapter Fifteen – Textile Fibers. FRSC 7104 Criminalistics I Professor Bensley. FRSC 7104 – Chapter 15 Objectives. After studying this chapter, the student should be able to:  Understand basic information about textile fibers and yarn

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Chapter Fifteen – Textile Fibers

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  1. Chapter Fifteen – Textile Fibers FRSC 7104 Criminalistics I Professor Bensley

  2. FRSC 7104 – Chapter 15 Objectives After studying this chapter, the student should be able to:  Understand basic information about textile fibers and yarn  Describe the three major methods of fabric construction  Recognize the important macro- and microscopic characteristics of fibers  Explain the major components of forensic fiber analysis and comparison

  3. FRSC 7104 – Chapter 15 Outline • Introduction • Definition • History of fibers • Natural

  4. FRSC 7104 – Chapter 15 Outline • Cellulose Derivatives

  5. FRSC 7104 – Chapter 15 Outline • Manufactured

  6. FRSC 7104 – Chapter 15 Outline • Natural Fibers • Animal • Vegetable • Mineral

  7. Clockwise (top left): Wool fiber (SEM), Mohair, Cashmere Goats, Silk fibers (polarized light)

  8. Clockwise (top left): Cotton fibers (SEM), Flax (linen), Ramie (China Grass), Jute

  9. Clockwise (top left): Sisal, Hemp, Kapok, Coir

  10. Asbestos Fibers Fiberglass Fibers

  11. FRSC 7104 – Chapter 15 Outline • Manufactured Fibers • Regenerated Fibers • Dry Spinning • Wet Spinning • Synthetic Fibers • Melt Spinning

  12. Rayon manufacturing process showing spinneret

  13. Wet and dry spinning techniques for rayon: (left above) wet spinning: the spinning solution enters (a), travels through the glass tube (b), coagulates in the bath of water (c) and is wound (d), on to bobbins (e) and (f); (right above) dry spinning: the spinning solution (a) is extruded through the spinneret (b), into a chamber of hot air (c) that evaporates the solvent, leaving a solid thread (d) Wet and Dry Spinning Techniques

  14. Nylon Stocking Production Process

  15. FRSC 7104 – Chapter 15 Outline • Yarn production

  16. FRSC 7104 – Chapter 15 Outline • Forensic Analysis of Fibers • Fracture (physical) match

  17. FRSC 7104 – Chapter 15 Outline • Microscopic comparison

  18. FRSC 7104 – Chapter 15 Outline • Birefringence (Polarizing light microscope) Polarized light views of fibers (Clockwise from top Left): Nylon, Cotton, Hemp, Acetate

  19. FRSC 7104 – Chapter 15 Outline • Cross-section Fiber cross sections: Nylon (L), Polyester (R), Various carpet fibers (below)

  20. FRSC 7104 – Chapter 15 Outline • Melting Points • Solubility • Dyes and Pigments (Color) • Instrumental Analysis Chapter Summary • Fibers are easy to analyze and are everywhere there are textiles • Most frequently encountered types of physical evidence • Color is one of most underutilized traits; should be analyzed spectrally or chemically • Combinations of characteristics make fibers very specific evidence

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