PERFORMANCE CHARACTERISTICS OF MATERIALS Flashcards
Fibre production: cotton
Cotton is grown in tropical parts of the world. when the seed pods of the plant (bolls) ripen, the seeds inside bolls become covered with fine cotton fibres. When the seed pod eventually bursts, it becomes a fluffy ball.
As the sun dries the fibres, they collapse and become flatter like a ribbon, then twisted
How short are fibres in the cottons Boll
short, about 2-5cm in length
Fibre production: linen
Come from the stem of the flax plant. The stalk is made up of bundles of fibres surrounding a centre pith. The fibres are separated from the parts of the plant that are not wanted.
Linen fibre characteristics in production
smooth round hollow centered tubes with cross markings down their length, they are about 3-4cm long.
Fibre production: wool
wool mostly comes from sheep. the sheep are sheared and the fleeces are sent to the mills for processing.
other luxury wools come from other animals - cashmere from goats, mohair from angora goats, angora wool from angora rabbit.
how long are wool fibres
between 4 and 39 cm long, staple fibres
fibre production: silk
comes from the cocoon of the silk caterpillar. It spins the cocoon with two triangular shaped filaments, held together with natural gum (sericin) one from each side of its mouth. It can only be made into silk if its boiled before the caterpillar breaks free as a moth, because this can ruin the filaments.
(regenerated fibre production) how is spinning solution made
using wood pulp - its cleaned and the cellulose is pressed into sheets. The sheets are dissolved in a solvent to make a thick, sticky liquid (spinning solution)
how is spinning solution made into viscose fibres using a spinneret (wet spinning)
the spinning solution is filtered to remove any undissolved particles, then pumped through a spinneret. The spinnneret is immersed in a bath of chemicals, which solidify the visocse filaments as they emerge from small holes in the spinneret. The fibres solidify from the outside inwards at an irregular rate.
The filaments are stretched before being wound on to a spool as filament yarns, or cut into short staple lengths.
The shape of the holes in the spinneret can be changed to make fibres of different characteristics
(production) Melt spinning of synthetic fibres
synthetic fibres are made from chemicals that come from oil. the chemicals are made into a polymer which is cut into small pieces. These are melted to make a spinning solution that is then pumped though spinnerets.
As long filaments leave the spinneret, they are passed through a stream of cold air that solidifies them, before they are stretched out three or four times their og length
what happens to the long filament fibres often?
they are cut to shorter staple lengths so that they can be mixed with other staple fibres like cotton.
Technical and modern materials
a new material that has been developed from its original form. It has special qualities suited to specific uses, but its not a smart material
some examples of technical and modern materials
Gore-Tex, Kevlar, nomex, phosphorescent textiles, reflective (glass beads), coolmax, micro-encapsulated fibres, purista/chitopoly (protects against bacteria, fabrics with electronics, geotextiles, materials using nano-tech, microfibres
Phosphorescent materials
materials that glow in the dark by transforming invisible energy forms into light
how can phosphorescent materials be used in textiles?
phosphorescent dyes can be incorporated into synthetic fibres and yarns, used for printing pastes or applied as surface coating
what is phosphorescent materials most purpose
for high visibility safety clothing
micro-encapsulated fibres and fabrics
health and cosmetic chemicals can be incorporated into the hollow centres of microfibres. The chemicals are released slowly or absorbed the skin of the wearer.
example of micro-encapsulated fibres
those that release scents
ceramic and carbon fibres are used in the production of nano fibres, why?
they are extremely lightweight and very strong
how are nano-fibres made?
using an electro-spinning process and are collected in the form of sheets as big as a football pitch
what are the nano-fibre sheets used for
breathable membranes. They allow perspiration to pass out of sportswear garments, and at the same time, prevent large water droplets and other potentially harmful particles passing through
Where can carbon fibres also be used
in the production of electro-conductive fibres which are used to make intelligent fabrics or wearable computers
where can ceramic fibres also be used
when incorporated with synthetic firbes through encapsulating the fibre or coating, it can give a fabric UV protection or make fabrics that regulate body temperature
example of UV protective fabrics
Esmo, sunfit
example of body-temperature regulating fabric
thermolite
why do filament and staple fibres with need to be twisted with other fibres to make yarn?
staple fibres are too short and filament fibres are too fine
what determines the strength of a yarn
the level of twists - low levels mean weaker fibres, they slip apart and rougher to touch. High levels increase strength and makes it smoother and denser; it also increases price.
staple yarn
a yarn made from short staple fibres that are twisted together to form a yarn
filament yarns + what happens when they are twisted with staple fibres
a yarn made by lightly twisting one or more filament fibres together. The filament fibres need to be cut to the same length as staple fibres in order to be twisted with them.
what makes staple yarns good insulators + moisture trappers
they are hairy, textured and duller in appearance - making them good at trapping air between the fibres. meaning they are good insulators and will make warm fabrics
how are multifilament yarns made
lightly twisting continuous filament fibres together. e.g nylon/ polyester
how are mono-filament yarns made
from a single, continuous filament
why are filament yarns not good insulators
they are smooth and therefore do not trap air between fibres, meaning they are not good insulators
Plied yarn
yarn made by twisting single yarns together to make a thicker yarn
single yarns
has staple fibres or filament fibres twisted together to make one single yarn
what does a ply of a yarn refer to
the number of strands that make up the yarn. yarns with higher number of plies are more durable as plies hold yarn together
corded yarns are made by twisting yarns with more than 1 ply together, where are corded yarns commonly used?
sewing and embroidery threads or industrial yarns that need to be very strong
why are fibres blended and mixed?
manufacturers include different fibres in a blend to mix the properties and enable a product to be better suited to the product
How can fibres be blended?
spinning two or more fibres together to make yarn. fibres must be the same length. The cut fibres are cute to the proportions needed in the mix - e.g 70% polyester and 30% cotton blends.
core-spun yarn
a component yarn with a central core yarn covered by other fibres
what is core-spun used for
producing stretch yarns or sewing threads - the core provide strength whereas the outside fibre is weaker but used for aesthetic purposes
what is a mixture
often refers to a fabric that has been woven with different warp and weft yarns
Main reasons for blending
- help reduce fabric costs
- give different effects in the fabrics texture and handle
- allow for novelty effects when fabric is dyed
- make a fabric with specific qualities for a particular end use
- make a fabric stronger
- make a fabric easier to care for
- enable fabrics to be more crease resistant
- allow fabrics to be heat-set
popular blend examples
polyester-cotton (polyester cancels out shrinking and slow drying, the cotton makes it soft to skin)
elastomeric fibres with others (small amounts can give a lot of stretch to fabrics as well as crease resistant
wool blends (makes it soft and warm, other fibre can give strength and abrasion resistance
what will happen if a yarn is twisted too much
it will cause the yarn to untwist itself and untwist and snarl
what do the tex or denier of a yarn relate to
the thickness of the yarn
how are tex and denier measured
by weighing a specified length of the yarn
what are the two types of yarns
textured and fancy
what are textured yarns
a continuous filament yarn that has crimps, crinkles and snarls heat- set into the filament, can be synthetic
describe textured yarns
they are more interesting, they can carry water through fine tubes created in and between yarns. textured yarns are softer and make more comfortable fabrics with more volume and less lustre. They have more elasticity as the crinkles and snarls help the yarn stretch out
what quality allows fibres to be heat-set
the thermoplastic nature of a fibre
methods of textured yarns
false twists (twisting tightly, heat set, then untwist)
bulked continuous filament (heat pushes yarns against cold surface)
air-jet texturing (compressed air directed at the continuous filament yarn)
fancy yarns
a yarn that has irregularities and other effects added to the length of the yarn to add interest
what is the most common form of fancy yarns
three yarns, each with different thickness for cooler effect, is twisted around one another - a fancy, a base and a tie thread.
what are the two main types of knits (looping of yarns)
warp and weft knits
knitting definition
knitted fabrics consist of yarns looped together in a variety of ways
weft knit
is made when one yarn travels the width of the fabric
what is the horizontal row of loops called in knit structures
course
what is the vertical row of loops called in knit structures
wale
how can weft knits be produced
by hand, on a domestic knitting machine or industrially
main features of weft knits
- has a lot of stretch and can easily be distorted
- drapes softly, easily takes shape of a figure
- fabrics do not crease easily
- fabrics trap air and are good insulators in still air, not in moving air
- ladders easily if snagged
- there is a distinct back and front of the fabric
variations of weft knits
single jerseys, plain knit, single jersey, double jersey, rib knits, jacquard knits
describe jacquard knits
complex patterns with different coloured yarns
hand knitting
weft knitting to make individual garments, sometimes using traditional patterns
what is warp knits more complicated structure like
contains many separate yarns that are interlaced sideways. The needles travel sideways for two or more wales before making a new loop
main features of warp knits
- less stretchy, therefore produces firmer fabric
- fabrics do not ladder and cannot unravel row by row
- there is greater scope for the production of a variety of fabrics
- it is faster than weft knitting, and the cheapest method of fabric production using yarns
variations of warp knits
net and lace structures.
why are there economic benefits to using knitted fabrics
knitting is faster process than weaving
production processes associated with hand and machine knitting
panel knitting
fully fashioned panels
whole garment knitting.
panel knitting process
fabric is knitted in individual panels of a specific width and length, and with a finished-off edge at the start. it is used for sleeve or skirt panels
fully fashioned panels
the garment parts are weft knitted to the exact shape and size required, and can be stitched together directly to make the garment. This method means that the fabric does not need to be cut to shape, and reduces waste. This is used in the manufacture of high-quality garments, all hand knitted garments are fully fashioned.
whole garment knitting
this process knits a garment three dimensionally in one piece, on a computer controlled knitting machine. Because there are no seams, the garment is more comfortable to wear and it can have greater fluidity than when seams break up the garments flow.
Manufacture is more sustainable as the yarns and threads required for each garment are used.
this is typically used for sports, medical and wearable smart technology
non woven fabrics
fabrics made directly from fibres that have not been spun into a yarn
non-woven fabrics examples
felts and bonded fabrics
main features of non-woven fabrics
- cheap to manufacture as they are made straight from fibres
- they do not fray when cut
- they are not as strong as woven or knitted fabrics
- they do not drape as well as woven or knitted fabrics
uses for bonded fabrics
disposable products, interfacings, filters, insulation and liners
wool felt
a thick, compact fabric made from wool fibres, using their natural felting ability to matt together with heat, mechanical action and moisture
wool felt disadvantage
expensive, as wool fibre is expensive
bonded fabrics are made from webs, what are the various ways bonded fabrics are held together
- adhesive bonding, special adhesive applied by spraying, dipping or spreading
- solvent bonding, solvent softens and fuses fibres together
- thermal bonding, uses the thermoplastic properties of fibres to fuse them together with heat and pressure
needle felts
a felt made from synthetic fibres that are matted together by mechanical action using barbed needles
bonded fabric
a fabric made from webs of fibres held together by an adhesive, a solvent or thermoplastic fibres
what determines a fibres properties
Properties are related to the internal fibre structure.
what affects factors like strength and absorbency.
The way the chains of molecules are arranged
if a fibre has high orientation (crystalline) , what will their property be regarding strength and abosrbency
they will be very strong but not absorbent as there is no where for the liquid molecules to go
what is another word for low orientation of molecules in a fibre
amorphous
what types of fibres are typically more absorbent as they have more amorphous regions?
Natural + regenerated fibres
what types of fibres are typically less absorbent as they have more crystalline regions?
synthetic fibres, the molecules are tightly packed therefore water has fewer places to go
what kind of products are typically made to be absorbent
it can become uncomfortable in clothing therefore the absorbency property is more useful in bathroom towels
one benefit and negative of absorbency in textiles
it can dye well however it can progress to other issues like shrinkage
strength and its relation to high orientated molecules
related to its ability to resist breaking under tension. If molecule chains are highly orientated in the fibre, the molecules share the load meaning its stronger
what process in the production of synthetic fibres causes molecules to become tightly packed making them strong?
the drawing process, it is stretched and that causes molecules to become orientated and lie parallel to the fibre axis.
why are natural fibres considered to be strong
Natural fibres are strong due to their low/high orientation mix
are fibres of high orientation or low orientation considered to be more elastic
highly orientated areas the molecule chains do not have spaces to move compared to less orientated. If these fibres are stretched, it will break. therefore low orientated fibres have more elastic ability
what kind of fibres set alight easily?
Cellulosic fibres (cotton) catch fire easily
what type of fibres melt or drip
synthetic fibres
what fibre is least flammable, or can put itself out
wool
what is thermal qualities in relation to fibres
determines whether a fibre is warm or cool to wear. The shape and formation plays some part in thermal qualities. It is the ability of a fibre to trap air.
what kind of fibres are not good at trapping air and why
cotton due to its smooth surface
what is lustre
ability of a fibre to reflect light to appear shiny. it can be used as an aesthetic quality but is sometimes unwanted
what property does a fibre need in order to reflect light
a smooth surface (e.g silk)
When choosing a fibre for a particular application, what do you need to be aware of
the requirements of the product so you can match them to the specific qualities of the fibres
Plant/cellulose fibres (cotton / linen / ramie) ADVANTAGES
- strong
- good at absorbing moisture (dyes well / won’t be subject to static electricity
- can be washed/ironed at high temp
Plant/cellulose fibres (cotton / linen / ramie) DISADVANTAGES
- Long to dry to as they are very absorbent
- poor insulator (good for hot conditions though)
- Crease and shrink easily, but this can be modified with finishes
ANIMAL/PROTEIN FIBRES wool advantages + disadvantages
AD: warm insulators / Stretch / water repellant / absorbency
DIS: Moth holes / shrinks badly / long time to dye / can be scratchy
ANIMAL/PROTEIN FIBRES Silk advantages + disadvantages
AD: warm / absorbent / strong / smooth / lustre / lightweight
DIS: weak when wet / creases badly despite natural elasticity
REGENERATED FIBRES (viscose) ADVANTAGES
- absorbent
- silky feel +lustre
REGENERATED FIBRES (viscose) DISADVANTAGES
- not very strong
- shrink + crease badly
- sets alight easily
- negatives are minimised w/ finishes*
NEW GENERATION LYOCELLS (lyocells, modal - comes from wood source) ADVANTAGES
- Sustainable biodegradable + recyclable viscose type fibres
- modified to be stronger
- less absorbent
- no crease/shrink
NEW GENERATION LYOCELLS (lyocells, modal - comes from wood source) DISADVANTAGES
- Expensive
- delicate
Synthetic fibres (polyester / polyamide / nylon) ADVANTAGES
- very strong even when wet
- resists abrasion
- lightweight
- smooth to touch + lustre
Synthetic fibres (polyester / polyamide / nylon) DISADVANTAGES
- dry quickly (not the same as waterproof)
- bad at absorbing so sticks to you in hotter months
Smart materials
a material that is able to react to its environment. It changes its properties as they are needed, and reverts back to its original form
what are examples of external stimuli which smart materials can react to
heat, light and power
what other fabrics are considered smart materials
those that can warn user of changes (loss of heat / presence of pollutants) or fabrics that incorporate electric components like music systems
what applications are smart materials used in typically
health and safety
sportswear
examples of what smart materials can do with fabric examples
- monitor body functions/give warnings
- maintain personal microclimate (stomatex, outlast)
- provide support and buoyancy
- chromatic properties, change colour in response to some situations
- have shape memory that adjust to differing temperatures
- self-cleaning (nano technology)
- use biomimetics that imitate nature (fastskin, stomatex)
- generate solar power when exposed to sunlight
- sense and track movement (SensFloor, smart carpets)
what must fibres used for textiles be
must be flexible and fine and have enough length/strength to be suitable to make fabrics.
what are all natural fibres (apart from silk)
Short fibres are natural fibres except silk (staple).
what are all regenerated fibres considered
All manufactured fibres are filament fibres (long)
what will impact the properties of a fibre
The source + physical shape of a fibre will have an impact on the properties. They each have different internal structure, it is possible to change/engineer the cross sectional shape of man-made fibres in order to add certain properties.
how is cottons structure impacted the properties is has/doesn’t have
When picked the fibre dries out, it collapses into a flattened bean cross section. The smooth surface prevents are from getting trapped, therefore making cotton cool to wear. The flat twisted form from the twists along its length does not reflect light well, meaning cotton doesn’t have a lustre.
how is linens structure impacted the properties is has/doesn’t have
Linen has a many-sided cross section and a long regular length to the fibres. This regular surface is a bale to reflect light quite well, which gives linen its slight lustre. Cross markings across the length (nodes), gives a slubbed look.
how is wools structure impacted the properties is has/doesn’t have
wool is a hair like fibre, the surface is covered by overlapping scales. The outer surface is covered with natural grease (lanolin) which makes it water repellent. The scales can lock together when in the presence of heat/moisture - making it shrink. This is why wool can be a hard fabric to care for without hand washing. Wools ability to insulate comes from the natural crimp of hair fibres that can stand away from each other and trap air.
Silks origin
silk comes from a silk worm which spins two filaments from each side of its mouth, the filaments are held together with sericin, which is a natural gum produced by the silkworm.
how is a regenerated fibre (e.g viscose) structure impacted the properties is has/doesn’t have
The spinning process involves setting the liquid fibres in a pool of chemicals, which set at irregular rates, making tiny grooves along the length of filaments. Giving the fibre an irregular cross - section.
Viscose reflects light, but as this is an unwanted property, often a delustering chemical is added to the spinning solution to reduce it.
The shape of the cross section of a fibre affects its lustre and handle. The shape of a manufactured fibre can be changed using spinnerets.
how is a synthetic fibre (e.g nylon/polyester) structure impacted the properties is has/doesn’t have
They are produced as a continuous filament + look like glass rods; this smooth surface enables them to reflect light as well as de-enable them to trap heat (poor insulators). The nylon cross section can be modified to a tri-lobe shape to be more comfortable when in contact with the skin.
