Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Composites > The Fibre Phase > Flashcards

The Fibre Phase Flashcards

(43 cards)

Start Studying
1
Q

What is the diameter of whiskers?

A

10-100nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the diameter of fibres?

A

5-15μm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the diameter of wires?

A

0.1-1mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are some aspects of whiskers?

A

-highly crystaline
- low flaws
- high strength
- high AR
- difficult to combine into a matrix
- expensive
- health concerns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the cost, modulus and strength of glass fibres

A

Low
Medium
Medium-hig

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the cost, modulus and strength of carbon fibres

A

high
high-veryhigh
high-veryhigh

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the cost, modulus and strength of Polymeric fibres?

A

medium-high
for all

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Are glass fibreanisotropic or isotropic?

A

Isotropic
same proterties parallel to fibre direction as perpendicular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the chemical structure of glass fibres?

A

series of interconnected tetrahedral SiO2 groups repeated in 3D
- silicon at centre
- Oxygen at vertices
- strong covalent bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 3 types of glass fibre used in composites and there properties?

A

E-glass(electrical) - good strength, stiffness, electrical and weathering properties CHEAP

C-glass(corrosion) - better corrosion resistance but lower strength

S-glass(strength) - Expensive but higher strength, tensile modulus and temp resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Applications of glass fibres

A

Marine
Automotive
Military
Construction
Storage
Baths

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How are glass fibres manufactured?

A
  1. weigh and dry oxide powders
  2. refractory furnace, melt and homogenise @1370*C
  3. refiner to complete homogenisation and remove bubbles @1340*C
  4. Forehearth @1250*C for extrusion through platinum bushings
  5. Draw fibres at 60m/s
  6. Quench fibres using air or water
  7. Sizing
  8. Process
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is the diameter of glass fibres controlled?

A
  • Viscosity of the melt
  • Size of bushing holes
  • Drawing speed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are different processing options of glass fibres?

A

Continuous strand - >100mm (long)
Chopped strand 3-100mm (short)
Hammer milled 30μm-3mm (particulate)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does sizing do to glass fibres?

A
  • protect fibres
  • binds fibres together
  • lubricate fibres to reduce abrasion
  • impart anti static properties
  • Chemical link between fibres and matrix
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does a typical sizing consist of?

A
  1. Protective polymeric film (PVA)
  2. Small molecule acts as lubricant
  3. Coupling agent to promote adhesion (organosilane)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What happens when glass fibres readily absorb water?

A

Na and Ca are leached out leaving it porous and weak

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What would an ideal sizing prevent for glass fibres?

Study These Flashcards
A

water affecting surface whilst providing chemical link to matrix phase
Strong covalent chemical bonds 350kJ/mol

19
Q

What happens to the surface energy of the glass fibres in water?

Study These Flashcards
A

reduces surface energy
if surface energy drops below liquid matrix, wettability of fibre is reduced and fibre-matrix is weakened

20
Q

What R group should be used for epoxy and phenolics?

Study These Flashcards
A

Use γ-Aminopropyl Triethoxy Silane (GAPS)

21
Q

What R group should be used for unsaturated polyesters?

Study These Flashcards
A

Use Methacryloxy Propyl Trimethoxy Silane

22
Q

What R group should be used for polyethylene and polypropylene?

Study These Flashcards
A

Use Vinyl Trimethoxy Silane + peroxide

23
Q

What R group should be used for polycarbonate nylons

24
Q

What is the chemical structure of carbon fibres?

Study These Flashcards
A

hexagonal arrangement of carbon atoms into a flat basal plane or layer
- strong covalent bonds
van der waals interations

25
what is the physical structure of carbon fibres?
- outer skin more ordered graphitic carbon - inner skin less ordered turbostratic carbo - turbostratic moslty orientated along fibre acis but folds.
26
27
Are carbon fibres anisotropic or isotropic?
highly anisotropic much stronger forces in fibre direction
28
What are the 3 types of Carbon fibre
HM - high modulus IM - intermediate modulus HS - high strength
29
Applications of carbon fibres?
Aerospace Automotive Sports
30
How are most carbon fibres manufactured?
Polyacrylonitrile PAN 1. Textile fibre 2. Stretch 3. thermoset 4. carbonise 1000*C inert atomsphere ( rid of O) 5. graphitize 2000-3000*C inert atmosphere (Removes any non carbon) 6. surface treatment 7. sizing
31
What is a second way to manufacture carbon fibers?
Pitch - stiffer but weaker
32
What are 2 surface treatment options for carbon fibres?
Oxidative process (oxygenate surface) Non-oxidative
33
What are the oxidative surface treatments for carbon fibres?
Gas phase - O with inert carrier @high temp over time Liquid phase - Strong liquid phase oxidising agents (nitric acid) or potassium permanganate Electrolytic - similar to liquid oxidising agents used in electrolyte solution with fibres as 1 electrode Plasma - plasma created from oxygen or air
34
What are the non-oxidative surface treatments?
Whiskerisation - Grow small whiskers of SiC perpendicular to fibre surface Sizing - coat fibres in polymer emulsion (solution deposition) - Deposit ionised polymer using fibre as electrode. initiate polymerisation within monomers (electro-deposition)
35
How can polymeric fibres obtain high modulus and strength?
High performance rely on alignment of polymer chains Extend chains when polymer is flexible Align chains when polymer rigid
36
How are Ultra High Molecular Weight Polyethylene (UHMWPE) made?
Gel-spinning hot drawing method 1. Dissolve PE in 0.5-5% decalin solution 150*C (removes chain entanglements) 2. Spin fibres (extrude) 130*C (forms fibre, removes entanglement and orientation) 3. Draw fibres under tension 155*C (provides most orientation)
37
How are aramid fibres made?
Dry-jet-wet-spinning method 1. dissolve in 15-20% conc H2SO4 solution ( forms crystal solution so rigid polymer chains align 2. Spin fibres (extrude) 80*C (Forms fibre) 3. Drawing needed only to reorient on exiting spinneret air gap
38
Applications of UHMWPE
Ballistic protection personal/vehicles
39
Application of aramids
kevlar ballistics
40
Properties of UHMWPE
High modulus and strength low density, tough, chemically inert low max usage temp
41
Properties of aromatic polyamides?
- high specific modulus and specific strength - low density and very tough - Poor in compression - Degrade in UV and absorb moisture easily
42
Why is it hard to surface treat polymeric fibres?
- fibres are highly aligned, stable polymer chains which depend on strong inter-chain interactions - Therefore difficult to bond to surface without compromising fibres
43
How can the adhesion of polymeric fibres be improved?
Oxidative plasma surface treatment short - oxidises surface improving wetability Intermediate - crosslinking @ surface eliminates weak material Long - pitted surface to be penetrated by resin (strength reduction)

Composites (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions