The document provides an overview of fibers, their classification into natural and manmade categories, and their significance as trace evidence in forensic science. It discusses the characteristics of fibers, including size and cross-sectional features, and outlines examination methods like microscopic analysis and various spectroscopies. The information emphasizes the importance of fibers in identifying sources and potential connections at crime scenes.

1. Presented By

2. Content

3. Introduction (Fibers)
• Fibers are thread like structures from fabric and other materials which are easily
identifiable under a microscope or smallest unit of a textile material that has a
length many times greater than its diameter.
• Its source can be determined by comparing it with fiber of a controlled sample.
• Just as hair left at a crime scene can serve as identification, the same logic can
reasonably be extended to the fibers that compose our fabrics and garments.
Fig.1 Photomicrograph of cotton
Fiber (450×)

4. Polymer
‘polymer’ poly many mer unit or
part
as very large molecules having high molecular mass (103 -107 u).
macromolecules
monomers.
covalent bonds.
Polymerisation.
• Classification Based on Source

5. Classification of fibers
Fibers
Natural Fibers Manmade/ Artificial Fibers
Animal Fibers
E.g Silk, wool,
Hair of Animal,etc.
Plant Fibers
E.g Cotton,
Leaf,
etc.
Synthetic Polymer
E.g Polyester, Nylon,
Dacron, Polyvinyl
derivatives, etc.
Natural Polymer
E.g Rayon,
Cellulose ester,
etc.
Mineral
Fibers
E.g Asbestos

6. Natural Fibers
two categories:
Fibers from plant source

7. Natural Fibers
Fibers from Animal source

8. Wool FiberCotton Fiber
Wood FiberCotton Dacron Fiber
Nylon Fiber Polyester Fiber
Nylon
Fig.2 Natural Fibers Fig.3 Manmade Fibers

9. Manmade/ Artificial Fibers
More than 50 percent

11. Significance of fibers as trace evidence
easily transferred

12. Collection and Packaging

13. Analysis of fibers

14. 1. Primary Examination
Fig. 4 Birefringence

15. 2. Chemical Examination

16. 3. Microscopic Examination
 Fiber diameter
o The fibers vary in size from 10 to 50 micrometers.
o The softer materials will have smallest fibres while the most durable materials
will have the largest fibers
o Also, for example, the finer woolen fibers are used for making clothing while
the coarser ones for using carpets. So again the size of the fibers can tell its
origin.
 Fiber cross section
o Basically, it is the cross section of the fibre that varies according to the type of
the fiber.
o The natural fiber have their origin from plants and animals and thus look
rough at the edges. This feature on the examination can actually reveal
whether the fibre is natural or man-made.
o Microtome is used to make cross-section

17. Fig.5 microscopic view of various cross Section of Fibers

18. Fig.6 Analytical Processing
Chart for Fiber Analysis

19. 3. Microscopic Examination
Atomic force microscopy

20. 3. Microscopic Examination
Other Methods Used For Examination:
• Raman Spectroscopy
• IR Spectroscopy
• UV-Visible Spectroscopy
A photomicrograph of a nylon
fiber displaying interference
colors when observed between
the crossed polars of a polarizing
microscope (100×).
Fig.7

21. Any Questions ?
• Reference :

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