Textiles & Fiber-Dye Interactions

What is a bicomponent fiber?

A fiber made of two polymers with different chemical or physical properties, spun from the same filament.

What are the advantages of bicomponent fibers?

They provide suitability for end products, such as creating thermally bonded non-woven fabrics or mimicking animal hair structures.

What is the function of a spinneret in fiber manufacturing?

A spinneret is a metal plate with tiny holes that shapes extruded fibers into specific cross-sectional forms.

What is the significance of fiber cross-section in forensic analysis?

The shape of a fiber when cut along its length is used to identify fiber type and manufacturing origin.

What are mordants in dyeing?

Mordants are substances that form coordination complexes with metal ions, which then bind to fibers, making dyes insoluble.

Azo dyes

(R-N=N-R) Form H-bonds between N and H in OH groups in fiber

-Ex: cotton

Ionic dyes

Fiber= + (cation/basic) dye= - (anionic/acidic)

- Ex: Nylon

Weft knitting

knitting forms loops in a horizontal manner using adjacent needles

Warp knitting

forms loops in a vertical manner with needles knitting a series of warp yarns.

yarn

Yarn is a continuous strand of textile fibers, filaments, or material suitable for weaving, knitting, or entangling to form a textile fabric.

fabric

A fabric is a textile structure produced by interlacing fibers with a substantial surface area in relation to its thickness.

What is the basic principle of weaving?

Weaving involves interlacing one warp yarn over one weft yarn and then passing it under the next weft yarn.

What characterizes a satin weave?

In a satin weave, the warp yarn floats over multiple weft yarns before passing under one.

What is the role of fibers in forensic examinations?

Fibers provide evidence that can associate suspects with a crime scene and can be individualized if reference fibers match those collected.

regenerated cellulose

A fiber made from cellulose through a regeneration process, such as rayon and viscose, which involves dissolving the polymer and reforming it.

What is the purpose of regenerated cellulose?

to produce continuous fibers and separate unwanted chemicals present in the raw cotton

What are some examples of natural fibers?

Natural fibers include cellulose fibers like cotton and animal fibers like silk and wool.

What is the process of acetylation in fiber production?

Acetylation is a chemical modification process that alters hydroxyl groups in cellulose to produce Cellulose acetate fibers

triacetate

Cellulose polymer where all the oh groups are acetylated

Acetate

Cellulose polymer where some of the OH groups are acetylated (2.5/repeat unit)

What are synthetic fibers?

Polymeric fibers produced from simple starting materials, such as polyesters and polyamides

What is the significance of fiber uniformity?

Fiber uniformity affects the properties and quality of the final textile product.

What is the difference between natural and synthetic fibers?

Natural fibers are derived from plants or animals, while synthetic fibers are man-made from chemical processes.

What is the purpose of using azo dyes in textiles?

Azo dyes are used for coloring fibers and form complexes with metal ions to enhance dye stability.

What is the role of cellulose in fiber production?

Cellulose serves as a primary raw material for producing regenerated fibers like rayon.

What does the term 'heat setting' refer to in fiber processing?

Heat setting is a process that stabilizes the shape and properties of fibers, often used in thermally bonded fabrics.

What is the importance of understanding fiber interactions in textiles?

Understanding fiber interactions is crucial for dyeing processes and achieving desired fabric properties.

Extrusion

A manufacturing process that forces polymer solution through a spinneret to form a synthetic fiber, affecting the uniformity nd properties

single ply

One strand of twisted fibers

Plied yarn

multiple yarn strands twisted together

plain weave

A basic weave in which each filling strand goes over and under each warp strand once.

twill weave

A weave in which the weft yarn is passed over and 2-3 warp yarns

knitted fabrics

fabric made by looping yarns together

Each yarn series in a knitted fabric is called a ________

stitch

Woven fabrics

Made by interlacing warp (longer) and weft (shorter) yarns together to produce a planar fabric

Z-twist yarn

a twisted yarn with the direction of twist conforming to the center bar of the letter "Z" (up to the right)

S-twist Yarn

a twisted yarn with the direction of twist conforming to the center bar of the letter "S" (up to the left)

Forensic Analyses for general classification of fibers

Polarized light microscopy, FTIR, Pyrolysis-gas chromatography, Microscopic properties, solubility, thermal analysis

Forensic Analyses for physical characteristics of fibers

Stereomicroscopy, light microscopy, scanning electron microscopy

Forensic Analyses for color of fibers

microspectrophotometry, thin layer chromatography, fluorescence