Test 2 Flashcards by Haley Walker

What is pulp?

very short and fine cellulosic fibers

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why do we use pulp in nonwovens

inexpensive and very absorbent

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what is a composite

bringing together of two or more materials, one of which must be a nonwoven

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what is a coform

marrying of two similar processes

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why are nonwovens important in medical textile applications?

they can be made from fine fibers which will then give a fiber a high surface area and barrier properties while being breathable

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how are nonwovens used in the composite industry

mold release fabrics and reinforcing fabrics that improve abrasion resistance, reduce corrosion, improve mechanical properties

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why are nonwovens useful in roads and highways

they help drain water and protect against frost heaves and cracks due to water freezing

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what is the major challenge in window treatments and what is done to correct this problem

light fabrics are non uniform and we will use layering and laminates

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why is the polypropylene the most used fiber in nonwovens

because its density is less than other fibers and you can make more fabric from the same bale compared to other fibers

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why are melt blown splitables being widely used in filters

they allow u to make very fine fibers and fabrics that will have a variety of pore shapes and size in which to trap particles

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5 desirable properties for hygiene applications

lightweight, soft and comfortable, skin friendly, flexible, absorbent, breathable

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5 desirable properties for crop covers

lightweight, water permeable, resistant to mold, uv resistant, air permeable, insect resistant

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3 reasons nonwovens suffer in other industries

low labor, highly technical, capital intensive

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how to make a low density abrasive pad

low density web sprayed with or dipped in adhesive that has abrasive particles in it. then heat the treat web to cure and assist particle/web stability

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5 properties used in nonwovens analysis

fiber orientation, bond to bond distance, mass nonuniformity, number of crossovers, and pore size and shape

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2 most important properties of nonwovens analysis and why

fiber orientation because it influences all other properties and mass non uniformity affects end us reliability

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dry laying web production

carding and airlaying

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fiber size of air laying

short or long fibers

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important fiber qualities of an air laying (6)

right length
cohesion
flexibility
can use about any type of fiber
need crimp
standard to coarse fibers

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uniformity of air-laid webs

good if properly opened

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problems w airlaying (3)

air flow leads to variability
uniformity is highly dependent on opening
fiber entanglement in the airstream can lead to web faults

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strengths of airlaying (5)

isotropic
very random
high loft and low density
broad range of fiber type
large range of basis wieght

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important fiber qualities of carding (3)

cohesion
crimp
length/ not as easy for short fibers

problems w carding (5)

not strong
static electricity
low fiber to fiber cohesion ‘
fiber breakage
permanent fiber elognation

strength of carding (4)

- the ability to blend fibers together - combination of multiple layers - wide range of fibers can be carded - wide range of basis weight

fiber qualities of wet laying (8)

- stronger - not seek to bond together - any natural or synthetic fiber - don't want it to have a lot of crimp - need special chemical on the surface - speciality type fibers - low surface tension - low fiber to fiber tension

problems of wet laying (5)

- have problem individulize because they are longer - expensive - requires a lot of energy - need a high-quality fiber - cant change from fiber type of fiber type easily

strengths of wet laying (3)

- high productivity - broad. range of products - can change the orientation of the fiber

2 different air laying processes and which produces what type of webs

``` route 1: -fiber prep -carding -bonding or cross lap to stacker - -finishing route 2: - stacking to bonding to finishing - bonding to finishing - heavier weight webs ```

why do we need to control fibers in airlaying?

so they dont tangle and choke up the machine

why do we trim the edges of the web after air laying?

since the velcoity on the outside of the machine is not as even as on the inside of the machine

6 properties of pulp

- bulk and absorbency - softness - wet strength - value - biodegradbale - abrasion resistance

what are we making in carding?

webs not sliver

how do we get a uniform web in carding?

we are feeding a uniform amount of fiber to the chute

what can we do to match the bonding types in carding?

change the profile of the web

what is tacking?

similar to needlepunching just with very small needles and only enough to hold them together enough to move

how do we add a higher basis weight and more lofty when carded?

cross lap then needlepunch and then caledner to add extra strength and compress the web

can we card bi-component fibers

yes

higher speeds will cause the fibers to do what

be more in the machine direction

if u run fibers through a traditional card what do u have to do

cross lap

5 things we expect from a cross laper

- will change fiber orientation - increase our basis weight - improve uniformity - composite type structure - increase fabric width

what kind of web can we get when cross lapping?

a heavier web

what does increasing overlaps do when carding

improves uniformity and weight

what is the BIGGEST problem with cross lapping?

lack of uniformity

what defects are associated with cross lapping? (3)

- voids: spaces with not an equal amount of fibers - creases: if it stalls it creates a crease in the fabric - slow

after carding, if there's a general low basis weight what kind of bonding can we do?

hydroentangle thermal bonding chemical bonding NO NEEDLE PUNCHING

higher basis weight

needle punch

what is the goal is wet laying?

to increase speed

what do we want out of wet laying ?

flexible and strong

important properties of wet laying? (6)

- aspect ration - tensile properties - flexural resistance - length - shrinkage - density

dispersion depends on (4)

- degress of fineness - fiber stiffness in aquesous solution - fiber crimp - fiber wettability

in wet laying once we seperate the fibers we need them to do what

stay seperated

after wet laying what do we have to do and why

bond because they dont have any strength

what kinds of fabric defects happen in wet laying?

- logs/sticks - ropes - dumbbells - fused fibers

how to make a good quality web in wet laying (4)

need good agitation no vortex fibers need low surface tension low fiber to fiber tension

important fiber properties of wet laying? (6)

- length - aspect ratio - tensile strength/elognation - flex resistance - shrinkage - density

when fiber length is increased in wet laying what happens?(3)

- less uniform - tensile strength increases up to a max - tear and burst strength increase up to a max