Introduction to Fibers II

Measuring Properties – Moisture Terms

• hydrophilic hydrophilic (Gr.: (Gr.: hydroshydros = water + = water + philosphilos = love)-fibers with = love)-fibers with an affinity to wateran affinity to water

• hydrophobichydrophobic (Gr.: (Gr.: hydroshydros = water + = water +phobos phobos = loathe)-fibers = loathe)-fibers with no affinity to waterwith no affinity to water

• The moisture properties of a fiber is determined, in large The moisture properties of a fiber is determined, in large measure, by its measure, by its chemical compositionchemical composition; does it have an ; does it have an affinity for water. affinity for water.

• Also Also hydrophilichydrophilic fibers may either absorb or adsorb water. fibers may either absorb or adsorb water. • AbsorbAbsorb – moisture penetrates into the fiber – moisture penetrates into the fiber• Adsorb Adsorb – moisture bound on the fiber’s surface– moisture bound on the fiber’s surface

Regain & Moisture Content

Super Scale Company

gramsW

Hot & Ready Oven Co.

100

Regain = (W – w)/w x 100%

Moisture Content = (W – w)/W x 100%

Mechanical Properties - Tenacity

weak material

strong material

A fiber that is made A fiber that is made from a less strong from a less strong material may be able to material may be able to carry more load than one carry more load than one made from a stronger made from a stronger material if the former is material if the former is greater in size.greater in size.

tenacity = strength/λ

Mechanical Properties - Elongation

extension

Similarly, a long fiber Similarly, a long fiber will extend further will extend further when stretched than a when stretched than a short fiber, even if short fiber, even if they are of the same they are of the same material.material.

elongation = “stretched length” – original length

strain = elongation/original length

Often these are multiplied by 100% to give percent elongation and percent strain

Measurement of Mechanical Properties

Pull Apart Co., Inc

Gauge Length

Fiber

Electronic Load Cell

Video Monitor

Pen Recorder

Computer Interface

Measurement of Mechanical Properties

1.1. Initial modulus Initial modulus (stiffness) – (stiffness) – resistance to resistance to deformationdeformation

2.2. Ultimate tenacity and Ultimate tenacity and strainstrain

3.3. Specific work of Specific work of rupture – energy rupture – energy (stored or released) (stored or released) at time of ruptureat time of rupture

Tenacity

Strain

u

u

2

31

Natural Fibers

Cellulosic

OO

CH OH

OHH

HO

HH

H

H

2

O

O

CH OH

OH

H

OH

H

HH

H

2

glycoside linkages

D-glucose unit

Cotton

• Seed hair fiberSeed hair fiber• Hydrophilic – affinity Hydrophilic – affinity

between the between the hydroxylhydroxyl groups groups (OH(OH--) and water (H) and water (H—OH)—OH)

• AdsorbsAdsorbs

cuticle (outer waxy layer)

primary wall

secondary walllumen

convolution

Wool

• 18 different 18 different amino amino acidsacids all with the all with the structure shown to the structure shown to the rightright H2 N C

R

H

C

OH

O

General amino acid

Polypeptide chain

N C

R1

H

C

H

O

N

H

C

R2

H

C

O

amide linkage

Crosslinking-cystine

O = C

CH•CH •S•S•CH •HC

H—N

C=O

N—H

2 2

cystine link

Wool

• Depending upon the Depending upon the source, wool fibers range source, wool fibers range in length from 38-375 mmin length from 38-375 mm

• round, and have a round, and have a diameter of about 25 µm. diameter of about 25 µm.

• The fibers can be identified The fibers can be identified by the scales on the by the scales on the surfacesurface

• FeltingFelting

Cortex

Scales

Wool

• 2 types of cortical cells2 types of cortical cells• Natural wavinessNatural waviness• Because each amino Because each amino

acid has different acid has different propertiesproperties• HydrophilicHydrophilic

• absorbsabsorbs

• Amphoteric –Amphoteric – behaves behaves like both acid and baselike both acid and base

para

ortho

Silk

• Protein fiber Protein fiber • The secretion of the larva The secretion of the larva

of the of the Bombyx moriBombyx mori moth, moth, used to form its cocoonused to form its cocoon

• The major fiber protein is The major fiber protein is fibroinfibroin, which is composed , which is composed of 15 amino acids in a of 15 amino acids in a polypeptide chainpolypeptide chain

• Very few cystine cross-Very few cystine cross-links links

• Not amphoteric.Not amphoteric.

Silk

• The larva secretes two 'D' The larva secretes two 'D' shaped filaments (called shaped filaments (called brinsbrins) simultaneously, held ) simultaneously, held together by the protein together by the protein gum gum sericinsericin. .

• The fibers are highly The fibers are highly regular and very lustrous.regular and very lustrous.

• The cocoon of the The cocoon of the silkworm contains about silkworm contains about 800-1200 meters of fiber 800-1200 meters of fiber (two strands); each fiber is (two strands); each fiber is about 10 µm thick about 10 µm thick fibroin

sericin

Asbestos

• Asbestos is the only naturally Asbestos is the only naturally occurring occurring mineralmineral fiber fiber

• There are 6 forms of asbestos: There are 6 forms of asbestos: Six minerals are defined as Six minerals are defined as "asbestos" including, "asbestos" including, chrysotilechrysotile, , amositeamosite, , crocidolitecrocidolite, , tremolitetremolite, , anthophylliteanthophyllite and and actinoliteactinolite

• Vast majority of textile fibers are Vast majority of textile fibers are chrysotile asbestoschrysotile asbestos, hydrated , hydrated magnesium silicate, magnesium silicate, [Mg[Mg33SiSi22OO55(OH)(OH)44] ]

• Flame resistantFlame resistant

chrysotilechrysotile

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• Monday: Short reportsMonday: Short reports• Tuesday: Manufactured FibersTuesday: Manufactured Fibers