POLYMER SCIENCE EXAMINATION
Multiple Choice Questions (MCQs)
Based on Synthesis, Structure, and Rheology Lectures
Student Name: _________________________ Date: _________________
Instructions: Choose the best answer for each question. Mark your answer clearly.
PART A: SYNTHESIS AND STRUCTURE (Questions 1-30)
1. What is the degree of polymerization?
- A) The number of polymer chains in a material
- B) The number of monomer units in a polymer molecule
- C) The molecular weight of the polymer
- D) The temperature at which polymerization occurs
2. Which synthesis mechanism produces water as a by-product?
- A) Polyaddition
- B) Polycondensation
- C) Polymerization
- D) Radical polymerization
3. What is Galalith made from?
- A) Fresh milk
- B) Spoiled milk
- C) Synthetic polymers
- D) Metal compounds
4. The melting temperature of alkanes increases with chain length because:
- A) Higher molecular weight
- B) Stronger van der Waals forces
- C) More crystalline structure
- D) All of the above
5. Which polymerization mechanism involves molecules with reactive ends?
- A) Polycondensation
- B) Polyaddition
- C) Radical polymerization
- D) Ionic polymerization
6. Phenolic resin is formed through which process?
- A) Polyaddition
- B) Polycondensation
- C) Radical polymerization
- D) Cationic polymerization
7. What happens to phenolic resin after cross-linking?
- A) Becomes soluble
- B) Becomes meltable
- C) Becomes brittle but strong
- D) Loses chemical resistance
8. Chain termination in radical polymerization can occur by:
- A) Recombination only
- B) Disproportionation only
- C) Both recombination and disproportionation
- D) Neither process
9. The Arrhenius equation describes:
- A) Polymer chain length
- B) Energy curve of chemical reactions
- C) Molecular weight distribution
- D) Crystallization temperature
10. What defines the constitution of a polymer?
- A) Spatial arrangement of chains
- B) Chemical structure of the molecule
- C) Temperature-dependent properties
- D) Mechanical properties
11. Polyolefins are characterized by:
- A) Only carbon in the backbone
- B) Presence of oxygen in the backbone
- C) Presence of nitrogen in the backbone
- D) Aromatic rings in the backbone
12. Tacticity refers to:
- A) Chain branching
- B) Crosslinking density
- C) Steric arrangement of side chains
- D) Molecular weight distribution
13. Which tacticity crystallizes most quickly?
- A) Isotactic
- B) Syndiotactic
- C) Atactic
- D) All crystallize at the same rate
14. ABS copolymer consists of:
- A) Acrylonitrile, butadiene, styrene
- B) Acrylonitrile, benzene, styrene
- C) Acrylic, butadiene, styrene
- D) Acrylonitrile, butadiene, silicone
15. Phase separation in copolymers can result in:
- A) Uniform distribution only
- B) Dispersed morphology only
- C) Sphere segregation only
- D) Various morphologies including dispersed and sphere segregation
16. Chain conformation describes:
- A) Chemical composition
- B) Spatial shape of the chain
- C) Synthesis method
- D) Molecular weight
17. The free energy of a polymer chain depends on:
- A) Internal energy only
- B) Entropy only
- C) Both internal energy and entropy
- D) Temperature only
18. For a single bond rotation, the energy profile shows:
- A) Constant energy
- B) Periodic energy changes
- C) Linear energy increase
- D) Exponential energy decrease
19. Primary bonds in polymers are:
- A) Van der Waals forces
- B) Hydrogen bonds
- C) Covalent bonds
- D) Dipole interactions
20. Secondary bonds between polymer chains include:
- A) Covalent bonds only
- B) Van der Waals, hydrogen, and dipole bonds
- C) Ionic bonds only
- D) Metallic bonds
21. The bonding energy of covalent bonds is approximately:
- A) 4 kJ/mol
- B) 20 kJ/mol
- C) 40 kJ/mol
- D) 400 kJ/mol
22. Van der Waals bonding energy is approximately:
- A) 4 kJ/mol
- B) 20 kJ/mol
- C) 40 kJ/mol
- D) 400 kJ/mol
23. Hydrogen bonding energy is approximately:
- A) 4 kJ/mol
- B) 20 kJ/mol
- C) 40 kJ/mol
- D) 400 kJ/mol
24. Dipole-dipole bonding energy is approximately:
- A) 4 kJ/mol
- B) 20 kJ/mol
- C) 40 kJ/mol
- D) 400 kJ/mol
25. What is the characteristic feature of polyurethane formation?
- A) Water elimination
- B) CO2 separation during foaming
- C) Heat generation
- D) Color change
26. The polymer backbone typically consists of:
- A) Only hydrogen atoms
- B) Carbon atoms with additional groups
- C) Only oxygen atoms
- D) Metal atoms
27. Radical polymerization requires:
- A) High pressure only
- B) High temperature only
- C) Activation to start the reaction
- D) Specific pH conditions
28. Cross-linking in polymers results in:
- A) Increased solubility
- B) Decreased mechanical properties
- C) Network formation
- D) Reduced chemical resistance
29. The degree of polymerization is calculated as:
- A) Number of polymer chains
- B) Molecular weight of polymer / Molecular weight of repeating unit
- C) Temperature of polymerization
- D) Time of polymerization
30. Which statement about polymer chain length is correct?
- A) All chains have identical length
- B) Chain length follows a statistical distribution
- C) Chain length is constant for all polymers
- D) Chain length depends only on temperature
PART B: STRUCTURE AND RHEOLOGY (Questions 31-60)
31. The free energy equation F = U - TS shows that:
- A) Internal energy causes ordering
- B) Entropy causes random distribution
- C) Temperature affects the balance between order and disorder
- D) All of the above
32. Which structure is easier to achieve in polymers?
- A) Branched molecules form ordered structures easily
- B) Unbranched molecules form ordered structures more easily
- C) Branching has no effect on structure
- D) Only cross-linked polymers can be ordered
33. Spherulites in polymers:
- A) Form from the outside in
- B) Form from the inside out with centrally symmetric growth
- C) Are always the same size
- D) Only form in amorphous polymers
34. The diameter of spherulites is typically:
- A) 1-10 nm
- B) 1-100 μm
- C) 1-10 mm
- D) 1-100 mm
35. Nucleating agents in polymers:
- A) Increase spherulite size
- B) Decrease spherulite size
- C) Have no effect on spherulite size
- D) Only affect crystallization temperature
36. As spherulite size decreases:
- A) Mechanical properties decrease
- B) Yield stress, strength, and toughness increase
- C) The material becomes more brittle
- D) Processing becomes more difficult
37. The critical molar mass Mc is:
- A) The minimum mass for entanglements
- B) About twice the mass required for load-bearing entanglements
- C) The maximum processable mass
- D) The decomposition mass
38. For polystyrene (PS), the critical molar mass Mc is approximately:
- A) 40,000 g/mol
- B) 70,000 g/mol
- C) 100,000 g/mol
- D) 200,000 g/mol
39. Increasing molar mass in polymers causes:
- A) Higher strength and toughness
- B) Better fatigue properties
- C) Poorer flow behavior
- D) All of the above
40. Short polymer chains in a distribution act as:
- A) Reinforcement
- B) Lubricant for good processability
- C) Nucleating agents
- D) Cross-linking agents
41. In semi-crystalline polymers, there are how many important temperatures?
- A) One (Tg)
- B) Two (Tg and Tm)
- C) Three (Tg, Tm, and Tc)
- D) Four (Tg, Tm, Tc, and Td)
42. The glass transition temperature (Tg) affects:
- A) Only amorphous phases
- B) Only crystalline phases
- C) Both amorphous and crystalline phases
- D) Neither phase
43. For processing thermoplastics, which bonds are broken?
- A) Primary covalent bonds
- B) Secondary valence bonds
- C) Both primary and secondary bonds
- D) No bonds are broken
44. The decomposition temperature (Td) represents:
- A) Reversible softening
- B) Irreversible decomposition
- C) Glass transition
- D) Crystallization temperature
45. In amorphous thermoplastics, the glass transition results in:
- A) Opacity
- B) Transparency
- C) Color change
- D) Crystallization
46. The operating temperature for amorphous thermoplastics should be:
- A) Above Tg
- B) Below Tg
- C) At Tg
- D) Temperature independent
47. For semi-crystalline thermoplastics, processing requires heating:
- A) Above Tg only
- B) Above Tm only
- C) Above both Tg and Tm
- D) Below both Tg and Tm
48. Elastomers are characterized by:
- A) High cross-linking density
- B) Weak cross-linking
- C) No cross-linking
- D) Variable cross-linking
49. Thermosets (duroplasts) are:
- A) Meltable and reformable
- B) Non-meltable due to high cross-linking
- C) Only processable below Tg
- D) Always transparent
50. DSC (Differential Scanning Calorimetry) measures:
- A) Mechanical properties
- B) Heat flow during heating/cooling
- C) Electrical properties
- D) Optical properties
51. In a DSC measurement, the peak maximum temperature (Tp) indicates:
- A) Glass transition
- B) Melting or crystallization peak
- C) Decomposition
- D) Processing temperature
52. Why are multiple DSC test cycles recommended?
- A) Thermosets may not be fully cured in first cycle
- B) Machine warm-up is needed
- C) Relaxation processes become visible
- D) All of the above
53. How does melting temperature change for stretched semi-crystalline thermoplastics?
- A) It becomes lower
- B) It remains the same
- C) It increases
- D) Thermoplastics cannot be stretched
54. The shear stress in fluid flow is given by:
- A) τ = η × γ̇
- B) τ = η / γ̇
- C) τ = γ̇ / η
- D) τ = η + γ̇
55. Most polymer systems exhibit which type of flow behavior?
- A) Newtonian
- B) Dilatant
- C) Pseudoplastic (shear thinning)
- D) Thixotropic
56. The shear rate for injection molding is typically:
- A) 10¹ - 10² s⁻¹
- B) 10² - 10³ s⁻¹
- C) 10³ - 10⁴ s⁻¹
- D) 10⁴ - 10⁵ s⁻¹
57. Bimodal molecular weight distributions provide:
- A) Improved processability only
- B) Better mechanical properties only
- C) Tailored processing and performance characteristics
- D) No advantages
58. The viscosity of polymer melts at processing temperature is typically:
- A) 10 - 100 Pa·s
- B) 100 - 1,000,000 Pa·s
- C) 1 - 10 Pa·s
- D) 0.1 - 1 Pa·s
59. Fast melting and processing of thermoplastics is important because:
- A) It saves energy
- B) Degradation rate increases exponentially with temperature
- C) It improves mechanical properties
- D) It reduces equipment wear
60. In thermosets during curing, viscosity:
- A) Continuously decreases
- B) Continuously increases
- C) First decreases, then increases
- D) Remains constant
PART C: ADDITIONAL QUESTIONS (Questions 61-75)
61. Which synthesis mechanism can be used to produce foamed materials?
- A) Polymerization
- B) Polycondensation
- C) Polyaddition
- D) Radical polymerization
62. How can radical polymerization be stopped?
- A) Raising the pressure
- B) Reducing the temperature
- C) Chain disproportionation and recombination
- D) Increasing catalyst concentration
63. What does the constitution of a polymer NOT describe?
- A) Type and number of atoms
- B) Spatial arrangement of chains
- C) Order of atoms
- D) Bonding types
64. The glass transition temperature (Tg) represents:
- A) Activation energy
- B) Gas temperature
- C) Glass transition temperature
- D) Gibbs temperature
65. The importance of Tg lies in:
- A) Temperature-dependent material properties
- B) Change of material state
- C) Entropy changes
- D) Gas state requirements
66. What advantage do cone-plate rheometers have over plate-plate rheometers?
- A) Less material is used
- B) Shear rate is more constant over diameter
- C) They are more modern
- D) There is no advantage
67. Is it important to know the flow behavior of thermosets over time?
- A) No, time plays a minor role
- B) Yes, viscosity increases with crosslinking
- C) Yes, high temperatures can occur during infusion
- D) Both B and C
68. The application range of polymers should be:
- A) Always above Tg
- B) Always below Tg
- C) Above Tg but below Tm for thermoplastics
- D) Temperature independent
69. Can thermosets be molten and formed repeatedly?
- A) Yes, crystalline areas allow this
- B) No, they are strongly cross-linked
- C) No, forming is only possible above Tg
- D) No, they can only be formed once
70. Which has the highest melting point among common polymers?
- A) 50°C
- B) 90°C
- C) 140°C
- D) 200°C+
71. The main difference between thermoplastics and thermosets is:
- A) Chemical composition
- B) Processing temperature
- C) Cross-linking density
- D) Molecular weight
72. Crystallization in polymers is favored by:
- A) High temperature
- B) Rapid cooling
- C) Slow cooling and nucleation
- D) High pressure only
73. The entanglement density in polymers affects:
- A) Color
- B) Transparency
- C) Mechanical properties and viscosity
- D) Electrical conductivity
74. Phase transitions in polymers can be:
- A) First-order only (melting)
- B) Second-order only (glass transition)
- C) Both first-order and second-order
- D) Neither type
75. The melt flow index (MFR) test measures:
- A) Mechanical strength
- B) Flow rate under standard conditions
- C) Thermal stability
- D) Chemical resistance
ANSWER KEY
Part A (1-30):
- B 2. B 3. B 4. D 5. B 6. B 7. C 8. C 9. B 10. B
- A 12. C 13. B 14. A 15. D 16. B 17. C 18. B 19. C 20. B
- D 22. A 23. C 24. B 25. B 26. B 27. C 28. C 29. B 30. B
Part B (31-60):
31. D 32. B 33. B 34. B 35. B 36. B 37. B 38. B 39. D 40. B
41. B 42. A 43. B 44. B 45. B 46. B 47. C 48. B 49. B 50. B
51. B 52. D 53. C 54. A 55. C 56. C 57. C 58. B 59. B 60. C
Part C (61-75):
61. C 62. C 63. B 64. C 65. A 66. B 67. D 68. C 69. B 70. D
71. C 72. C 73. C 74. C 75. B
End of Examination
Total Questions: 75
Time Allowed: [To be specified by instructor]
Good Luck!