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Polymer Matrix Composites Principles and Manufacturing
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Polymer Matrix Composites Principles and Manufacturing
Polymer Matrix Composites Principles and Manufacturing
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1
Question
What is the structure of thermoset polymers?
Page 1
Answer
3D network that cures irreversibly.
2
Question
What is the structure of thermoplastic polymers?
Page 1
Answer
High-molecular-weight linear chains with no chemical change on heating.
3
Question
How does processing viscosity differ between thermosets and thermoplastics?
Page 1
Answer
Thermosets have low viscosity before cure allowing low temperature/pressure processing. Thermoplastics require very high viscosity needing higher temperature and pressure.
4
Question
Can thermosets be re-formed after processing?
Page 1
Answer
No, they cannot be remelted and reformed.
5
Question
What is the typical mechanical behavior of thermosets versus thermoplastics?
Page 1
Answer
Thermosets show low strain to failure and low fracture energy. Thermoplastics have high strain to failure and high fracture energy.
6
Question
How does storage life differ for thermosets and thermoplastics?
Page 1
Answer
Thermosets have restricted storage life for some systems. Thermoplastics have unlimited shelf life and are post-formable and reprocessable.
7
Question
Which composite has the best fatigue resistance under tension-tension loading?
Page 1
Answer
CFRP is best, followed by AFRP intermediate, GFRP lowest.
8
Question
Which composite performs best in impact resistance?
Page 1
Answer
GFRP best, AFRP intermediate, CFRP and high-modulus CFRP lowest.
9
Question
How do PAN-based carbon fibers compare to pitch-based in overall properties?
Page 1
Answer
PAN better overall properties, handling, and strength. Pitch higher stiffness and conductivity but poorer compression, shear, and often tensile strength.
10
Question
What are the advantages of PMCs over metals?
Page 1
Answer
Low weight, corrosion resistance, tailoring possible. Disadvantages include poor conductivity, impact sensitivity, environmental sensitivity.
11
Question
What is the formula for extrusion helix angle?
Page 1
Answer
\( A = \tan^{-1} \left( \frac{\text{pitch}}{\pi D} \right) \)
12
Question
What formula calculates injection mould cavity shrinkage?
Page 1
Answer
\( D_c = D_p + D_p S + D_p S^2 \)
13
Question
What is the die swell ratio formula?
Page 1
Answer
\( r_{sd} = \frac{D_p}{D_d} \)
14
Question
How is parison thickness after swell calculated?
Page 1
Answer
\( t_p = r_{sd}^2 t_d \)
15
Question
What relates blow mould thickness to parison?
Page 1
Answer
\( D_p t_p = D_m t_m \)
16
Question
What is the micromechanics formula for longitudinal modulus E1?
Page 1
Answer
\( E_1 = E_f V_f + E_m V_m \)
17
Question
What formula gives transverse modulus E2 in micromechanics?
Page 1
Answer
\( \frac{1}{E_2} = \frac{V_f}{E_f} + \frac{V_m}{E_m} \)
18
Question
What helix angle results from the extruder screw parameters given?
Page 2
Answer
14.4 degrees.
19
Question
What screw speed is required for the given extruder flow rate?
Page 2
Answer
About 44 rpm.
20
Question
What is the mould cavity dimension for D_p = 120 mm and S = 0.025?
Page 2
Answer
123.075 mm, so about 123.08 mm.
21
Question
How can injection moulding shrinkage be reduced?
Page 2
Answer
Higher injection pressure, longer compaction time, lower moulding temperature, avoid thick sections, use fillers.
22
Question
What is the diameter swell ratio in the blow moulding example?
Page 2
Answer
r_sd = 22 / 18 = 1.222.
23
Question
What parison and container wall thicknesses result in Q6?
Page 2
Answer
Parison t_p about 2.39 mm; container t_m about 0.44 mm.
24
Question
What E1 and E2 values result for the micromechanics example?
Page 2
Answer
E1 = 378.4 GPa and E2 = 11.3 GPa approximately.
25
Question
What layers comprise a typical vacuum bagging layup?
Page 2
Answer
Breather layer, vacuum bagging film, bleeder layer, perforated release film, peel ply, composite laminate, release film, tool; sealant tape and vacuum port.
26
Question
What feature defines the typical autoclave cycle?
Page 3
Answer
Staged heating with intermediate dwell for temperature equilibration in thick lay-ups.
27
Question
What distinguishes chain polymers from network polymers?
Page 4
Answer
Chain polymers are very long molecular chains that may be linear, branched or ladder-type (e.g., PE, PP, PVC, PTFE, PAN, PMMA, PVAC). Network polymers are 3D interconnected by cross-linking or direct formation (e.g., epoxies, unsaturated polyesters, phenol-formaldehyde).
28
Question
What are heterochain polymers and examples?
Page 4
Answer
Backbone atoms other than carbon; e.g., polyamides, polyesters like PETP.
29
Question
How do thermosets affect PMC fabrication compared to thermoplastics?
Page 4
Answer
Thermosets: low-viscosity pre-cure for wetting at low T/P, irreversible cure, longer process/restricted storage. Thermoplastics: high viscosity high T/P, remeltable, high strain/toughness, short process/unlimited storage.
30
Question
What chain polymers examples are listed?
Page 4
Answer
PE, PP, PVC, PTFE, PAN, PMMA, PVAC.