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Materials Identification > fibre analysis > Flashcards

fibre analysis Flashcards

1
Q

what is tenacity

A

overall structure of a fibre

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2
Q

what is durability

A

the ability of a fibre to withstand rubbing or friction

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3
Q

what are pilling properties

A

the formation of balls of loose fibres on the surface of a fabric resulting from abrasion

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4
Q

what is dimensional stability

A

The ability of a fibre to maintain its original shape, neither shrinking nor stretching

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5
Q

what is elastic recovery

A

The ability of a fibre to return to its original length after it is stretched

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6
Q

what is creep

A

how the fibre response to a constant stretching force

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7
Q

what is flexibility

A

The ease by which fibres can be bent of folded which affects the overall drape

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8
Q

what is resilience

A

how easily a fibre returns to original state after creasing

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9
Q

what is absorbency

A

the ability of a fibre to tale in moisture

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10
Q

what are thermal properties

A

how well the fibre insulates the wearer

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11
Q

what are the two fibre types

A

natural

synthetic or man-made

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12
Q

what are the three natural fibres

A

animal
vegetable
mineral

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13
Q

animal fibres

A

proteinaceous materials
subdivided into 3 groups according to their structure
silks (fibroin), wool (keratin) and hair (keratin)

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14
Q

vegetable fibres

A

subdivided into 3 groups according to derivation
seed fibres, bast (stem) and leaf fibres
seed fibres = cotton, kapok and coir
bast or stem fibres = flax, ramie, hemp and jute
leaf fibres = sisal, abaca and new Zealand hemp

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15
Q

give one example of a mineral fibre

A

asbestos

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16
Q

what type of fibre is silk

A

animal

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17
Q

silk

A

obtained from larvae of silk moth
Silk is spun from 2 glands in the mouthparts of the creature
Produces two individual strands which are then encased in a protein known as sericin

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18
Q

what type of fibre is wool and hair

A

animal

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19
Q

wools and hair

A

Variety of sources from the most common ovine Wool (sheep) to unusual wool such a Chiengora (dog)
Animal fibres of this type are primarily composed of the protein keratin made of sulphur rich amino acids but varies by species and even diet

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20
Q

ovine (sheep) wool

A

Soft, strong, elastic, warm, breathable and comparatively inexpensive
All wools show obvious signs of scaly morphology and the number of scaled will vary by breed of sheep
cross section shows round morphology

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21
Q

medulla cells

A

often dead and air filled

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22
Q

cortical cells

A

spindle shaped cells packed together

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23
Q

cuticle cells

A

forming a tough outer sheath of top facing overlapping scaled which vary between and hence can be fairly discriminating

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24
Q

vegetable fibres

A

Primarily cellulose with the addition of hemicellulose, lignin’s, pectin’s, water soluble proteins, fats and waxes
Significant differences found in fibre length, diameter, cell wall shaped and general appearance

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25
Q

what type of fibre is cotton

A

vegetable

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26
Q

what type of fibre is hemp

A

vegetable

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27
Q

cotton

A

strong, soft, elastic, warm, breathable

The fibre is easily dyed with a range of materials allowing a huge range of colours to be produced

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28
Q

asbestos

A

Asbestos is a naturally mineral fibres used in a variety of applications
A generic term for a number of silicate fibre types with high elasticity and high resistance to corrosion, wear and tear and heat… It will not burn
Used industrially where it was once mixed with concrete and other materials to produce fire resistant board, insulation etc.
Remains used in some friction materials and some fireproofing

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29
Q

what are man-made chemicals derived from

A

petrochemicals

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30
Q

synthetic fibres

A

The aim is to produce something that replicates natural fibres, but either improves upon some of the limitations of the original or produces a cheaper alternative
Improvements may include greater tolerance to chemical action, heat, shrinkage, greater strength, greater absorbency or less practically, improved appearance, texture or the greater ability to be permanently coloured

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31
Q

which two sources can semi-synthetic fibres be regenerated from

A

biological

mineral

32
Q

cellulose fibres - semi-synthetic fibre

A

common of regenerated fibres

sub-classes of it

33
Q

viscose rayon - semi-synthetic fibres

A

inexpensive

very soft, comfortable

weak with poor abrasion and low wet strength

34
Q

viscose rayon manufacture - semi-synthetic fibres

A

cellulose material - wood pulp

treated with NaOH

treated with CS2 forming sodium cellulose xanthate

little water and NaOH added, viscous liquid formed and then extruded in hardening bath

hardening bath consists of H2SO4, sodium and zinc sulphates and glucose

35
Q

lyocell-tercel

semi-synthetic fibres

A

modern variant of viscose

performs well with soft, strong, wrinkle resistant fibre with strong water absorption properties

fibre obtained direct from solvent without derivative formation

raw bleached cellulose dissolved in N-methylmorpholine N-oxide

material extruded and drawn in air after which they are set in dilute amine oxide which hardens the fibres

can be washed or dried and undergo any post-processing

36
Q

cellulose esters -diacetate and triacetate

semi-synthetic fibres

A

soft smooth fibres which dries quickly and has lustrous appearance and is colourfast

acetate performs badly as it distorts and wrinkles very easily, has poor thermal properties and is weak fibre so dry clean only

raw bleached cellulose reacts with acetic anhydride, acetic acid and sulphuric acid which acetylates the hydroxyl groups

undergoes controlled hydrolysis to produce dictate or triacetate

dissolved in acetone or other solvent and extruded into fibres

37
Q

spinning

made-made fibres

A

polymer is prepared in a concentrated, viscous form, either in a solvent or in some molten state

material extruded through tiny holes in a device known as a spinneret, a plate with a number of precision bored holes

spinneret can produce fibres of various shapes and diameters giving rise to fibres with variable cross sections although in practise this is normally carried out with melt spun fibres

38
Q

wet spinning

A

used for polymers which need to be dissolved in a solvent for spinning such as acrylic, rayon, aramid and modacrylic

spinneret generally submerged in a bath containing a solution which causes the emerging fibres to precipitate and solidify to strands

strands are then taken up and are normally drawn to increase their strength and align the polymers chain in the same direction thereby increasing fibre tenacity

setting solution varied according to the fibre being manufactured and is normally sulphuric acid for rayon or thiocyanate for acrylic

39
Q

dry spinning

A

used for polymers which need to be dissolved in a solvent for spinning such as acetate and triacetate and acrylic

instead of the spinneret being submerged in a chemical bath, it lies at the top of a warmed chamber

as the material emerges from the spinneret, the solvent evaporates causing the polymer to coagulate and form individual fibres

hot air of warmed inert gases carry the solvent away where it can be recovered and reused

strands are taken up and normally drawn

40
Q

melt spinning

A

simplest of all processes and one used for polymers which can be melted such as nylons, polyester and various others

polymer, in pellet form is melted in an inert atmosphere and then forced through the spinneret into a cooling chamber

strands are then taken up and normally drawn to increase overall strength

cross sectional shape is easily controlled using spinning which is a very useful point for fibre identification

41
Q

spinning - cross sectional shape

A

fibre cross sectional shape may be result of spinning process where the process causes fibres to become crenelated

with melt spun fibres it is possible to engineer the fibre cross section to produce certain specific properties such as treated softness of wicking

42
Q

round cross sectional shape

A

no major longitudinal striations uniform diameter

43
Q

bilobal cross sectional shape

A

kidney or dog-bone shaped single of double striation

44
Q

trilobal cross sectional shape

A

parallel striations that appear to move

45
Q

hollow cross sectional shape

A

single continuous hollow forming a black core

46
Q

complex cross sectional shape

A

multiple striation appearing irregular

47
Q

delustrant

man made fibre

A

Engineering fibre shape and cross section can help to alleviate the problem to some extent but may not always lead to favourable hand

It is possible to include materials that help dampen the lustre of fibres and in most cases this is Anatase

Not only does Anatase help prevent light reflection, but its inclusion may also roughen the fibre surface dampening reflectivity

Delustrant appears as dark coloured ‘dots’ within the fibre matric and the size, shape, appearance, abundance and general distribution are useful for comparative purposes

Although the presence of delustrant does not serve to identify a specific fibre type, it is a useful indicator of man-made fibre and may be use as a comparison tool

48
Q

condensation polymerisation

A

chemical condensation reaction in which water or acid is produced as a by-product

49
Q

addition polymerisation

A

produced by joining molecules using a double bond or free radical reaction

50
Q

polyamides - nylon 6,6 and nylon 6

synthetic fibre

A

Soft, smooth fibres with controllable lustre

High strength fibres with god abrasion resistance and elastic recovery

Uncommon in modern clothing but used for manufacture of seatbelts, tire cord, ropes and other high strength materials including gun parts

Resists attack by some chemicals, molds and mildew

A fibre derived from simple pre-cursor organic materials

Produced in two forms: nylon 6,6 and nylon 6

51
Q

polyamide nomex and kevlar

synthetic fibres

A

Aromatic polyamides having at least 85% of their amide linkage directly attached to two aromatic rings

By comparison to traditional fibres, aramids lack the properties requires to produce soft, comfortable fashionable clothing

Both fibres are extremely strong with good abrasion resistance

52
Q

polyamides - acrylic

A

Smooth, soft warm fibres comparable to wool although considered a bit on the cheap side

Moderate strength fibres with fair abrasion resistance

May be seen in jumpers, hats, rugs, curtains and various plastic items such as garden furniture

Light and chemical resistant but flammable and staticky

Fibre derived from acrylonitrile and a copolymer which are polymerised and dissolved in a solvent

The material produced then undergoes dry spinning or wet spinning in a bath of dilute solvent

53
Q

polyamides - dynel and verel

A

Many of the same properties as acrylic and similar uses

However modacrylic is somewhat flame retardant and will self extinguish

Modacrylic is as the name suggests a modified acrylic fibre where between 35% and 85% of the fibre consists of polyacrlonitrile monomer units and the remainder consists of some other sub-unit

This is normally vinyl chloride, vinylidene chloride or vinyl bromide

Once polymerised, the fibre is dissolved in solvent and dry spun

54
Q

acid dyes

A

polyamides, wools, silk and polypropylene

55
Q

azo dyes

A

cellulosic fibres

56
Q

what type of fibre does dye come under?

A

man-made

57
Q

basic dyes

A

acrylics, polyester and polypropylene

58
Q

direct dyes

A

cellulosic fibres

59
Q

disperse dyes

A

polyester and acetate

60
Q

metaliised dyes

A

wool

61
Q

sulphur dyes

A

cellulosic fibres

62
Q

vat dyes

A

cellulosic fibres- denim

63
Q

pigment

A

polypropylene, viscose, acrylic, polyamide and polyester

64
Q

what are pigments

A

insoluble particles of strong colour which are normally added to the melt during spinning

clearly man-made fibre normally melt spun

65
Q

when is the dying process completed

A

after spinning to may factor as part of the spinning process

66
Q

what are the 3 things used to identify dyes

A

CI number

generic name

commercial name

67
Q

CI number in dyes

A

all dyes are given a 5 digit colour index number of CI number

dyes which come as multiple salts may include a sixth

68
Q

generic name in dyes

A

all dyes are given a generic name which may indicate use

69
Q

commercial name in dyes

A

comes from the manufacturer

70
Q

before silk fibres can be used

A

Before the fibres can be used, sericin casing is degummed by dissolving in dilute alkaline revealing two translucent fibres of triangular cross section
Composed of the protein fibroin, which is rich in alanine, glycine and serine and contains no sulphur containing amino acids
Doesn’t have the same unpleasant smell as burning as hair fibres

71
Q

what percentage of cotton is cellulose

A

95

72
Q

cotton after maturation

A

the fibre walls shrink, and the central hollow lumen becomes smaller and flattens which evokes convolutions or twist which improves flexibility and allows better interlocking in yarn

73
Q

mercerisation in cotton

A

Can be treated in a process called mercerisation in which the fibre is treated with NaOH and elongated causing the fibre to swell
Produces a more lustrous, softer, stronger fibre that takes up dye better

74
Q

nylon 6,6

A

Nylon 6,6 is produced from a condensation reaction between adipic acid and hexamethylene diamine, the 6,6 comes from the use to two 6C precursors, the reaction is a simple condensation

75
Q

nylon 6

A

Nylon 6 is slightly inferior in its properties particularly in regard to its melting point

Nylon 6 is produced from a ring opening reaction between molecules of caprolactam – the 6 comes from the use of a single 6C precursor, the reaction is a ring opening forming a linear chain polymeric molecule

76
Q

nomex

A

Nomex has excellent thermal resistance properties and is used in flame retardant properties and is used in flame retardant clothing for pilots, firefighters and racing drivers
Nomex is produced from a condensation reaction between meta-phenylenediamine and isophthaloyl chloride producing HCl condensate

77
Q

kevlar

A

Kevlar has incredible strength being on a weight for weight basis five times stronger than steel!

It is used far ballistic protection, stab resistance gloves, tyre ply and for top end racing sails

Kevlar is produced from para-phenylenediamine and terphthaloyl chloride producing very linear polymer chain of high strength

Materials Identification (17 decks)

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