The document discusses the classification and examination of natural and man-made fibers, detailing their sources, properties, and production methods. It covers fiber types including vegetable, animal, and mineral fibers, as well as man-made options derived from both natural feedstock and manufactured feedstock. Furthermore, it outlines techniques for fiber analysis in forensic science, such as microscopic examination, spectroscopy, and thin-layer chromatography, emphasizing their importance in identifying and comparing fibers for investigative purposes.

1. FIBER EXAMINATION
Nandini Katare

2. Fibre-Types and
Classification

5. Introduction
Natural Fibres
Fibres that are
obtained from natural
sources like plants
(cotton, linen, jute),
animals (wool, silk),
and minerals
(asbestos).
Man-made Fibres
Fibres that are
manufactured from
synthetic polymers or
modified natural
polymers through various
chemical processes like
polymerization, melt
spinning, and solution
spinning.
Textiles are made from a variety of
natural and man-made fibres, each with
their own unique properties and
production processes.

6. Natural Fibres
•Vegetable Fibres
Cellulose-based fibres obtained
from various plants, including
cotton, linen, jute, flax, ramie,
coir, sisal, and hemp. These
fibres are used for textiles,
paper, ropes, cords, coir mats,
and industrial fabrics.
•Animal Fibres
Protein-based fibres obtained
from animals such as sheep,
goats, rabbits, and silkworms.
Examples include wool and silk.
•Mineral Fibres
Naturally occurring mineral
fibres, with asbestos being the
only one used extensively,
though it is now being phased
out due to its suspected
carcinogenic effects.

7. Vegetable Fibres
Vegetable fibres are cellulose-based
and include important natural fibres
such as cotton, linen, jute, and flax.
These fibres are widely used in the
textile industry, as well as for
industrial and household
applications.

8. Animal Fibres
Wool
Wool is a protein-based natural fibre
grown by animals like sheep, goats,
rabbits, and camels. Sheep provide
almost 90% of the total wool
produced globally. Wool grows at a
rate of about 1.25 cm per month and
is sheared after the full growth of the
thick coat.
Silk
Silk is another protein-based natural
fibre, produced by the silkworm. The
silkworm secretes a viscous fluid
from its glands and wraps itself with
the filament to form a cocoon. The
rate at which the silkworm produces
a 1 to 2 kilometer long filament is
close to 50 cm per hour.
Global Wool Production
In 1996, there were more than 12
crore sheep in the world, with India
having 4.5 crore sheep. However,
India's share of world wool
production was much lower.
Silk Production
The silkworm cocoon is subjected to
stoving (steaming), and the silkworm
dies inside the cocoon. The filament
is then collected for use in textile
production.

9. Man-Made Fibres
• Derived from
Natural
Feedstock
These fibres are
derived from natural
sources like cellulose
(viscose rayon, lyocell,
tencel) and rubber
latex. Viscose rayon
was the first truly
man-made fibre,
discovered over 100
years ago. More
recently, solvents for
cellulose have been
found, allowing for
the production of
cellulose fibres
directly from a
cellulose solution,
under the trade
names Lyocell and
• Derived from
Manufactured
Feedstock
These fibres are
produced from low
molecular weight
chemicals that are
converted into fibre-
forming polymers
through
polymerization.
Synthetic fibres like
polyamides (nylon 66,
nylon 6), polyesters,
acrylics, and
polypropylene are
obtained through this
route. Elastomeric
fibres like spandex
and lycra are also
similarly made.
• Miscellaneous
Fibres
This category includes
man-made fibres like
glass fibres and
metallic fibres (silver,
gold).

10. Derived from Natural Feedstock-Regenerated
Viscose Rayon
Previously made through a complex process
involving the conversion of cellulose to
cellulose xanthate, now using direct cellulose
dissolution methods.
Lyocell and Tencel
Direct cellulose dissolution methods have led
to the development of these advanced
cellulose-based fibres.
Chemically Modified Cellulose Fibres
Small quantities of cellulose diacetate and
cellulose triacetate are also produced as
chemically modified cellulose fibres.
Rubber Fibres
Rubber latex from rubber trees is used as a
natural feedstock to make rubber fibres for
textile and other industries.
Fibres derived from natural feedstock share similarities with natural cellulosic fibres,
offering comfort and suitability for apparel in tropical and hot climates, though they
may exhibit greater non-uniformity and complexity compared to man-made fibres.

11. Fiber examinations
•Fiber examinations involve a comparison of
samples from known and questioned sources to
determine whether they are originated from
the same source.
•Textile fibers can be exchanged between
individuals, between individuals and objects
and between objects.

12. •Fibers are associated with a specific source,
such as fabric from the victim, suspect or
scene.
•Whether a fiber is transferred and detected is
also dependent on the nature and duration of
the contact between the suspect and the
victim and/or scene and the persistence of the
fibers after they have been transferred.

13. Analysis
•There are three basic activities involved in an
analysis:
•1. Collection of a representative sample
•2. Preparation of the sample for analysis
•3. Analysis using appropriate methods

14. Physical Matches
• A physical match occurs when two or more pieces of fabric or
cordage can be reconstructed to prove they were previously one
continuous piece of fabric or cordage.
• This examination is conducted by describing and documenting any
cut, torn or damaged edges on questioned items and their
correlation to like areas on known items. Photography is the
recommended method for physical matching record.

15. Microscopic examination of Textile
Fibers
• Several types of light microscopes are used
including stereo binocular comparison microscope,
a compound light microscope equipped with
polarized light, fluorescence and interference.
• In certain instances, the scanning electron
microscope may yield additional information.

16. • They are mounted on glass microscope slides in a mounting
medium under a cover slip.
• The fibers are then examined microscopically with a combination
of various illumination sources, filters, and instrumentation
attached to a microscope to determine their polymer type and
record any microscopic characteristics.
• Known and questioned fibers are then compared to determine if
they exhibit the same microscopic characteristics and optical
properties.

17. Thin-Layer Chromatographic
examination of Nonreactive Dyes in
Textile Fibers
• TLC is an inexpensive, simple, well documented technique
that, under certain conditions, can be used to complement
the use of visible spectroscopy in comparisons of fiber
colorants.

18. Principle of tlc
•The principle of the method is that the
dye components are separated by their
differential migration caused by a
mobile phase flowing through a
porous, adsorptive medium.

19. • Forensic analysis of fiber colorants using TLC should be
considered for single fiber comparisons only when it is not
possible to discriminate between the fibers of interest using other
techniques, such as comparison microscopy (brightfield and
fluorescence) and microspectrophotometry in the visible range.
• The application of TLC may serve to discriminate between fibers,
or it may confirm their similarity.

20. Analytical
Techniques for Fibre
Examination
.

21. Microscopic Examination
Stereomicroscopy
Used to give a
general overview of
the fibre, helping
identify color,
texture, and possible
damages.
Polarized Light
Microscopy (PLM)
Used to determine
the optical properties
of fibres, including
birefringence,
refractive indices,
and pleochroism,
which can help
distinguish between
natural and synthetic
fibres.
Comparison
Microscopy
Used to compare
questioned fibres
with known
standards for side-
by-side analysis of
physical and optical
properties.
Microscopic examination is a fundamental technique in
fibre analysis, providing valuable insights into the
morphology, color, and surface features of fibres, which
are crucial for establishing links between suspects, victims,
and crime scenes.

22. Fourier Transform Infrared
Spectroscopy (FTIR)
Fourier Transform Infrared
Spectroscopy (FTIR) is a powerful
analytical technique used in
forensic science to identify the
chemical composition of fibres. By
analyzing the characteristic
infrared absorption spectrum of a
fibre, FTIR can determine the
molecular structure of the
material, which is unique to each
type of fibre. This allows forensic
experts to compare the FTIR
spectrum of an unknown fibre
sample to reference spectra,
enabling them to accurately
identify the fibre type.

23. Raman Spectroscopy
Non-Destructive Analysis
Raman spectroscopy provides
detailed molecular information about
the fibre without damaging or
destroying the sample.
Comprehensive Fibre
Analysis
Raman spectroscopy can be used to
analyze both natural and synthetic
fibres, making it a versatile technique
for forensic investigations.
Differentiation of Dyes and
Additives
Raman spectroscopy can be used to
differentiate between different dyes
and additives present in the fibre,
providing valuable information for
comparison and identification.
Minimal Sample Required
Only a small amount of sample is
needed for Raman spectroscopic
analysis, making it an efficient and
non-destructive technique.

24. Scanning Electron Microscopy (SEM)
Fiber Surface Morphology
SEM image showing the
detailed surface texture and
structure of a natural fiber, such
as cotton or wool. This allows
forensic scientists to observe
surface features that can be
used to identify and compare
fibers.
Fiber Damage Analysis
SEM image highlighting the
physical damage and wear
patterns on a synthetic fiber,
such as polyester or nylon. This
can provide important clues
about the history and origin of
the fiber evidence.
Fiber Cross-Section
Examination
SEM image of a cross-section of
a fiber, revealing its internal
structure and shape. This can
be useful for differentiating
between natural and man-
made fibers based on their
distinctive cross-sectional
profiles.
Elemental Composition
Analysis
SEM-EDX analysis showing the
elemental composition of a
fiber, which can be used to
identify the presence of any
inorganic components or
contaminants that may be
unique to a particular source.

25. Ultraviolet-Visible (UV-Vis) Spectrophotometry
Fibre Dye Analysis
Dye Identification
Dye Differentiation
Colour Characterization

26. Thin Layer Chromatography (TLC)
Fibre Coloration
Analysis
Thin Layer
Chromatography
(TLC) is used to
analyze the dyes
within fibres. It can
help identify the
specific dyes used
to color the fibre.
Dye
Separation
TLC separates the
dyes in the fibre
into their individual
components,
allowing forensic
scientists to
examine the
specific dye
composition.
Dye
Identification
By analyzing the
separated dye
components,
forensic experts
can identify the
particular dyes
used to color the
fibre. This can help
match fibres to
known samples or
manufacturers.
Comparison to
Standards
The dye profile
obtained from TLC
can be compared
to reference
standards to
determine the
specific dyes
present in the
fibre, aiding in the
identification and
comparison of
fibres.

27. Other Analytical Techniques
• X-ray Diffraction (XRD)
Determines the crystalline structure
of fibres, particularly important for
synthetic fibres like nylon and
polyester. Comparing the diffraction
patterns can help identify different
types of synthetic fibres.
• Fluorescence Microscopy
Many fibres, especially synthetic
ones, exhibit fluorescence under UV
light. Fluorescence microscopy can
help distinguish between fibres of
similar colors by observing how they
emit light when exposed to UV rays.
• Thermal Analysis (DSC and TGA)
Differential Scanning Calorimetry (DSC) measures the heat flow associated
with fibre melting, crystallization, or decomposition to differentiate between
fibre types based on their thermal properties.
Thermogravimetric Analysis (TGA) determines the thermal stability and
composition of fibres by measuring the change in mass as a function of
temperature to identify the type of polymer in synthetic fibres.

28. Thank You