Figure 1
For questions 1-3, refer to Figure 1 which shows a stress-strain curve for a thermoplastic polymer.
1. The approximate value of the tensile strength of the polymer is
a) 8 MPa b) 9 MPa c) 10 MPa d) 11 MPa e) 12 MPa
2. The Young’s modulus is approximately
a) 0.1 MPa b) 1 MPa c) 10 MPa d) 100 MPa e) 1000 MPa
3. The percent elongation-to-break is approximately
a) 5% b) 12% c) 500% d) 1200%
In Figure 2, stress-strain curves are shown for three polymers, A, B, and C. Use this figure to answer questions 4, 5, and 6.
Figure 2
4. Which polymer is the most brittle?
a) A b) B c) C
5. Which polymer is the toughest?
a) A b) B c) C
6. Which polymer has the highest tensile strength?
a) A b) B c) C
7. In Figure 3, stress-strain curves are shown for a thermoplastic polymer below, above, and well above the glass transition temperature.
Which curve corresponds to a temperature below the glass transition temperature?
a) A b) B c) C
Figure 3
Use the table of mechanical properties of polyimide films (Chem. Mater. 10(3), 734-739, 1998) to answer questions 8 and 9:
|
Polyimide |
Tensile strength (Mpa) |
elongation-at-break (%) |
Young’s modulus (GPa) |
|
PIa |
105 |
6 |
2.18 |
|
PIb |
91 |
5 |
2.59 |
|
PIc |
72 |
5 |
2.28 |
|
PId |
97 |
4 |
2.70 |
|
PIe |
75 |
5 |
2.34 |
|
PIf |
99 |
7 |
2.85 |
8. If a film of the polymer is stretched, which polymer will be the hardest to stretch initially?
a) PIa b) PIb c) PIc d) PId e) PIe f) PIf
9. If fibers were made from these polyimides, which polymer would produce a fiber that holds the most weight?
a) PIa b) PIb c) PIc d) PId e) PIe f) PIf
10. Based on chemical structure, which of the following polymers would make the most flexible fiber?
a) –(CH2)n- b) -(CH2)2OCO(C6H4)COO- c) –(CH2)6CONH(CH2)