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Man-made (synthetic) Fibers

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by

Brooke Braun

on 3 October 2013

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Transcript of Man-made (synthetic) Fibers

Spencer Anderson
Brooke Braun
Thomas Etheridge


Jeff Matejovsky

Type
Collection & Preservation
Cross Section
Man-made (Synthetic) Fibers
Definition: (man-made fiber) fiber created from natural materials or by chemical processes.
The history of man-made fibers is less than a century old; until 1910, there were no synthetic or chemical fibers. Today, by mixing different components, manufacturers can take basic fibers and make them more waterproof or more absorbent, warmer or cooler, thicker or thinner, stiffer or more supple. Some, like polyester and spandex, combine well with natural fibers, making fabrics that wrinkle less or are more form-fitting.
Solid Round
*Standard cross section for most synthetic fibers.
*Minimum surface to volume ratio.
*"Cheap" type of fiber.
*Hollow void enclosure with fiber.
* Usually round (Not necessarily though)
Features:
*Highly specific surface area
* Lower density at the same diameter
*Thermal insulation properties due to trapped air
*High specific rigidity, as long as hollow void does not collapse
* A non-shiny appearance
NOT MOISTURE WICKING
Trilobal
*Rigidity and Resilient
*Reflecting surface
*Scatters light
*Hides dirt
*Sparkling appearance
HOLLOW
Often used in carpets
Ribbon
* Large flat surface
* Reflects light (appears sparkly)
* Blends with other fibers well
* Easily splits into microfibers
4-DG
* Good for moisture transport
* Has many grooves (moisture wicking capillaries)
* Thermal insulation due to deep grooves
* Good filtration
Bowtie
* Side-by-Side filament yarn
* Good stretch recovery
* Heli-coiled fibers
Polypropylene
*Made of olefin fiber
*Results in a high crystallinity (72-75%)

* Strong
* Flexible
* Being studied on how it can be synthesizer
* Used in engineering plastic.
Acrylic
*Acrylic fiber is a synthetic fiber that closely resembles wool in its character.
*fibers which contain a minimum of 85% acrylonitrile in their chemical structure are called "Acrylic Fibers".

* The fiber has a kidney shaped cross-section
* Resistance to damage by moths and chemical substances
* Lightweight, soft, and warm, with a wool-like touch

*Used for: Sweaters, socks, fleece wear, Carpet, blankets, car tops, boat covers, filtration materials, car batteries
Polymer
Carbon Fiber
Polyester
Nylon
Polyethylene
Polypropylene
Rayon
Acrylic
PEEK
Spandex
Polymer
A long strand of monomers that make up a chain (High weight)
Polyester
*Long strands of synthetic polymer and monomers that make-up esters.

*Esters are formed when alcohol reacts with a carboxylic acid

*High Strength
*Resistant to shrinking
*Low moisture absorption
Nylon
*Formed from long strand of synthetic poly amide that has reoccurring amide groups (-NH-CO-)

*Excellent Strength
*Flexibility
*Washable
Polyethylene
*Made of polymerized polyethylene units made of micro filaments (One Strand)

*Low specific gravity (floats in water)
*Mildew and insect resistant
*Sunlight resistant
Rayon
*Composed of regenerated cellulose. It is made from purified cellulose, primarily from wood pulp.

*Abrasion resistant
*Chemical resistant
*Highly resistant to machine use
PEEK
Known as "Polyetheretherketone" made of thermoplastic poly-condensed multi-filament.

*Highly vacuum compatible
*Mechanical wear resistant
*Chemical resistant
Spandex
It is polyurethane-poly-urea co-polymer
Carbon Fiber
*High density
*Abrasion resistant
*Flexibility
*Carbon fibers are twice as stiff as steel
Testing Techniques
*Depending on the class of the fiber, each polarized plain of light will have a characteristic index of refraction.
*TESTS are preformed to confirm that all of the fibers involved belong to the same broad generic class
*Microscopic comparison of color and diameter with microscope.

Composition of Synthetic fibers
Also called graphite fiber or carbon graphite, carbon fiber consists of very thin strands of the element carbon.
Found in:
*Workout clothing
*Waistbands of clothing
*Womens' hair accessories

Often times mixed with nylon
1) It is the job of the investigator to identify relevant carriers of fiber evidence.

Preservation
*WHERE FIBERS ARE VISIBLE AND NOT FIRMLY ATTACHED, OR IF FIRMLY ATTACHED AND OBJECT IS TO LARGE TO SEND TO LABORATORY
2) Relevant articles of clothing should be packaged carefully in paper bags.
3) Container size should correspond to size of article
4) Leave fibers INTACT.

a) diagram and note exact location and approximate number of fibers

b) label object and package in a container so that fibers cannot become dislodged in transit

c) label packaging with appropriate information

*WHERE FIBERS ARE VISIBLE AND FIRMLY ATTACHED TO AN INANIMATE OBJECT TO BE TRANSPORTED TO THE LABORATORY
Collection
a) after diagramming and noting each location and the number of fibers present, carefully remove CLEAN tweezers and package

b) place fibers in a small pill box, glass vial, or other tightly sealed container. Fibers may also be placed in small folded paper bindles.

c) label packaging with appropriate information.
Police collecting synthetic fibers

Differentiating Characteristics
1) All of the natural fibers come from nature

2) Length of the fiber is nature given

3) Fibers are found in staple filament for.

4) Some short staple fibers are found with long staple fiber

5) No need to spinneret for spinning process

6) NO need of chemical solution for yarn production

7) Not possible to change fiber structure
NATURAL
1) Synthetic fibers are completely man made

2) Length of the fiber is controlled by man

3) It is found in filament form but sometimes it could be converted into staple or cut length

4) No question about short or long staple fiber

5)Spinneret is essential for filament production

6) Chemical solution is essential for yarn production

7) Easy to change in fiber structure.
SYNTHETIC
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