15570081 Identification of Textile Fibers

8/9/2019 15570081 Identification of Textile Fibers

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TYPES OF TEST

The Non technical Test FEELING TEST

BURNING TESTS

The Technical Test MICROSCOPIC TEST

CHEMICAL TEST


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Tests for identification

Handle/Feel Test

Visual Examination

Burning testTwist on Drying

Floatation Test

Microscopic analysis

Chemical Analysis


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Requirements for tests:

Preparation of test specimen

Apparatus for microscopic examinationReagents used for chemical tests

Other tools and equipment


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THE NON-TECHNICAL TESTS

Feeling test

Burning test


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FEELING TEST

The feeling test requires perception ifit is to be of any value.

Skilled perception is acquired onlyafter handling many different fabricsover a period of time.

Limitations of this test becomeapparent when examining andcomparing fabrics of different fibercontent.


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BURNING TEST

To recognize the composition of fabrics bythe burning test ,the sample of fibre, yarn offabric should be moved slowly towards asmall flame and the reaction to heatcarefully observed .One end of the sampleshould be put directly into flame to

determine its burning rate andcharacteristics. The burning odour should benoted and the characteristics of the ashsuch as amount ,form, hardness and colour

should be examined.


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IDENTIFICATION OF FIBRES THROUGH BURNING

TEST

Cotton

When ignited it burns with a steady flameand smells like burning leaves. The ash left

is easily crumbled. Small samples of burningcotton can be blown out as you would acandle.

Linen

Linen takes longer to ignite. The fabricclosest to the ash is very brittle. Linen iseasily extinguished by blowing on it as you

would a candle.


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SilkIt is a protein fibre and usually burns readily,not necessarily with a steady flame, andsmells like burning hair. The ash is easily

crumbled. Silk samples are not as easilyextinguished as cotton or linen.

WoolIt is also a protein fibre but is harder to

ignite than silk as the individual "hair" fibresare shorter than silk and the weave of thefabrics is generally looser than with silk. Theflame is steady but more difficult to keepburning. The smell of burning wool is likeburning hair.


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Man Made Fibres

AcetateAcetate burns readily with a flickering flamethat cannot be easily extinguished. Theburning cellulose drips and leaves a hard

ash. The smell is similar to burning woodchips.

AcrylicAcrylics burn readily due to the fibre content

and the lofty, air filled pockets. A matchdropped on an acrylic blanket can ignite thefabric which will burn rapidly unlessextinguished. The ash is hard. The smell isacrid or harsh.


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Nylon

Nylon melts and then burns rapidly if theflame remains on the melted fibre. If you

can keep the flame on the melting nylon, itsmells like burning plastic.

Polyester

Polyester melts and burns at the same time,the melting, burning ash can bond quickly toany surface it drips on including skin. Thesmoke from polyester is black with a

sweetish smell. The extinguished ash is


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Rayon

It is a regenerated cellulose fibre whichis almost pure cellulose. Rayon burnsrapidly and leaves only a slight ash.

The burning smell is close to burningleaves.


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LIMITATION OF BURNING TEST

It is apparent that many fibers havesimilar burning reactions that mightcause doubt and occasional

confusion.


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TECHNICAL TESTS

There are certain technical tests performedfor identifying various fibers. These tests require high technology laboratory equipment a

nd are much more reliable than the non technical fibre tests.

Technicals tests require high skilled personnel and technical know how of handling chemi

cals and their accurate analysis. These testsare very valuable for those fabrics that are ablend of different yarns and also have certain special properties including flame retardance etc.


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TYPES OF TECHNICAL TEST

Microscopic test

Chemical test


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MICROSCOPIC TEST

Microscopic test is a technical test that involvesidentifying the fabric with the help of a microscope with a magnification of minimum 100 power.

The test can easily distinguish between fibers.

The test identifies the natural fibers more easilyas compared to man made ones.

Synthetic fibers are very similar in appearanceand the increase in the number of varieties, makes it a little tough to distinguish the fibers even under a microscope.


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MICROSCOPIC TEST FOR NATURAL

FIBERS

COTTON:

It is a single elongated cell.Under the microscope, itresembles a collapsed,spirally twisted tube with a

rough surface. The thin cell wall of the fiber

has from 200 to 400convolutions per inch.

LINEN: Under the microscope, the

hair like flax fiber showsseveral sided cylindricalfilaments with fine pointedends.

The fiber somewhat


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WOOL: Under the microscope , wools

cross section shows threelayers- epidermis, cortex andthe medulla.

SILK: It appears somewhat elliptical

and triangular in cross sectionwhen we see under themicroscope.

It is composed of fibroin,consisting of two filaments,called brin which is held

together by sericin.


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MICROSCOPIC TEST FOR MANMADE

FIBERS

RAYONS: Rayon fibers have a

glasslike luster under themicroscope and appear to

have a uniform diameterwhen viewedlongitudinally.

ACETATE: The cross sectional viewhas a bulbous or multilobalappearance withindentations.

These indentations appearas occasional markings or


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NYLON: The basic microscopic

appearance is generally fine ,round, smooth, andtranslucent.

It is also produced inmultilobal cross-sectionaltypes.

POLYESTERS: Generally, polyester fibers are

smooth and straight and thecross-section is round.

This general characteristics

may be altered to achieve


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ACRYLICS: The methods of manufacturing of theacrylic fibres differ, the appearances varyaccordingly.

ACRILAN ACRYLIC: It has a bean-shaped crosssection, its longitudinal appearance is straightand smooth.

ORLON ACRYLIC: It has a flat, nut-shaped crosssection.

CRESLAN ACRYLIC: It has an almost round crosssection.

MOD ACRYLICS: it is of two types verel modacrylicand SEF modacrylic


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SPANDEX:Spandex fibers are unique inappearance, they appear to be groups of fibersfused together.

GLASS: The fiber is smooth, round, translucent,highly lustrous, and quite flexible.

Asbestos fibre


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CHEMICAL TESTS

Chemical tests are another technical means ofidentifying fibers. But chemical tests are notintended for the general consumers.

Different types of chemical tests are undertakento establish the identity of the fibers used.

These tests give accurate and precise analysis.

The tests are conducted in research laboratories.


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TYPES OF CHEMICAL TEST

Stain Test:Also known as the Double Barrel Fibre Identification(DBFI), the test is based on the theory that each

fibre has its own distinct two- colour reaction whentreated with stain.A fibre will turn to a particular colour in thepresence of dilute acetic acid and to some other

specific colour when stained in the presence of amild alkali.


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Solvent Test:The test involves treating the fibres in certainsolvents for identifying them. The technical test is

becoming difficult to conduct as most of themanufactured fibres and their blends are chemicallysimilar. There is no individual chemical or solventtest for separating or identifying the fibres incombinations.


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Distinguishing animal from vegetablefibres with an acid

As strong alkali destroy animal substances, a 5%of soda lye solution in water can be used toeliminate wool and silk fibers from a sample thatcontains a mixture of fiber. The vegetable fibreswill not be affected by this solution.


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Distinguishing vegetable from animalfibres with an acid

As dilute acid destroy vegetable fibers, a 2%sulphuric acid solution can be used. A drop ofsolution is placed on the sample, which is thenpressed with a hot iron. The spotted area willbecome charred if the sample is cotton linen or

rayon.


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DISTINGUISHING SILK FROM WOOL:

The use of concentrated cold hydrochloric acid willdissolve the silk and the wool fiber swells.

DISTINGUISHING NYLON FROM OTHERFIBRES:

If the fabric is thought to contain nylon, the fabricmay be immersed in a boiling solution of sodiumhydroxide. The nylon is insoluble in such a solution.


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DISTINGUISHING POLYESTERS FROMOTHER FIBRES:Polyester is soluble in hot meta cresol; however ,unlike acetate it is not soluble in acetone, and

unlike nylon it is not soluble in concentrated formicacid.

DISTINGUISHING ACRYLICS FROMOTHER FIBRES:Acrylic fibers will dissolve in 70 percent solution ofammonium thio cyanate at 130 degree Celsius but

the other fibers will not.


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DISTINGUISHING LINEN FROM COTTON

Cotton and linen are immersed in a 1% solution offuchsine in alcohol to give red rose colour. Later ,

they are washed and immersed into ammonia, linenretains the red coloration but cotton does not.

DISTINGUISHING GLASS FIBERS FROM OTHER

FIBRES:There are two specific solvents for quickidentification of glass fibers, they are hydrofluoricacid and hot phosphoric acid.


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This technical fibre identification test has the followingadvantages and limitations

Advantages

More reliable than the non technical tests. Used for both man made fibres and natural fibres. Easily conducted.Limitations Certain manufacturing and finishing processes like

mercerizing, affects the appearance of the fibres underthe microscope. Very dark coloured fabrics cannot be identified under

microscope. Dye stuffs must be removed from fabrics.


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Fiber Identification

Strong

More elastic

Translucent&

uniform

Burns & stops

Out of flame

Leaving darkhard beads

Dissolves

slowly

---Looses

strength

---------------Nylon

Translucent&

uniform

Lofty & more

voluminous

Burns & stops

Out of flame

Leaving dark

hard beads

Dissolves &

Turns yellowish

brown

Turns

yellowish

brown

---Looses

strength

& dissolves

slowly

---------------Acrylic

Resistant to

chemicals

Translucent&

uniform

Burns& stops

leaving semi

Dissolves

slowly

transpera

nt hardbeads.

Dissolves

slowly onprolonged

treatment

---------------Polyeste

r

Rough crimpy

fibers

Scales

structure

Self extinguishing

Leaves crushable

Black beads

Fish

Dissolves

slowly

---Dissolves

slowly

------Dissolves-do--do-Wool

coating

Delicate

lustrous

filaments

Densed centreline Uneven

Self extinguishing

Leaves crushable

Black beads

Dissolves---Dissolvespartial;ly

------Dissolves slowly

DissolvesLoosesstrength

Silk

Soft filaments

good luster

Longitudinal

regular lines

Burns

continuously

leaving grey ash

of burning paper

smell

Dissolves

quickly

DissolvesDissolvesDissolv

es onheating

Turns

yellow

Gets

weakened

Swells &

slowlydissolves

SwellsViscose

serations

Brittle & resistant

to chemicals

Opaque thick-do-

black ash

Dissolves

slowly

Dissolves

onprolonged

heating

---------Color

turnspale

------Coir

-Rough handleLongitudinal

irregular lines

-doDissolves-do-do------

-

-do--do--do-jute

Resistance to

alkalis.

Longitudinal

twists.

Burns

continuously

leaving grey ash

of burning paper

smell

Dissolves

quickly

Dissolves

on heating

&looses

strength

Dissolves

slowly

Opens

up

Turns

yellowish

WhitenedSwells&

Shines

swellsCotton

RemarksMicroscopic

View

Burning in

Flame

Sulphur

ic acid

70%

Sulphur

ic acid

15%

Nitric

acid

70%

Nitric

acid

15%

Hydro

chloric

acid

40%

Sodiu

m hypo

chlorid

e

Caustic

soda

25% sol.

Soda ash

40% sol.

test

fiber


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THANK YOU

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15570081 Identification of Textile Fibers

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