Question

polymer physics

yes otherwise?

1. To determine the Tg of polymers, which method is NOT applicable? (a) dilatometry, (b) OM, (e) DSC. (d) HDT. o d ) T0 sho dai n0 nar onom (o) itivo bos ed do o lT ed 2. To determine the Tm of polymers, which method is NOT applicable? (a) POM, (b) WAXD, (c) SEM, (d) DSC. MGT0 2lsbom tods bne M001 To ulubom oY ed mlog 3. To determine the crystallinity, which method is NOT applicable? (a) density, (b) DSC, (c) wide angle X-ray, (d) GPc M1RAY0 s 4. To observe the craze of polymers, we can use (a) DSC, (b) TEM, (c) WAXD, (d) SAXS. ot im A b st 0 5. For PE crystals, which one is NOT right? (a) normally it is orthorhombic, (b) it can form banded 01spherulites, (c) the single lamellar crystal is usually triangle shape, (d) the lamellar thickness is larger at high crystallization temperature, (e) there are five chains in one unit cell. s6 When using TEM to observe lamellar thickness, which one is NOT right? (a) using the diamond knife to cut the sample, (b) ultra-thin films (-50 nm thick) are required, (c) staining is required to enhance the contrast, (d) the magnification factor is -5000X, (e) the v msa im o odqm th of lamellac is -1 olo o r bon 7. To observe spherulites using POM, which one is NOT right? (a) Maltess cross pattern is normally found, (b) POM can distinguish the a-form and B-form of iPP, (c) banded spherulites with ring patterns are always observed, (d) crystal growth rate can be measured, (e) the spherulitic diameter is normally 10 um. 8. The Young's modulus of rubber is about (a) 1GP , (b) 1MPa, (c) 1 kPa, (d) 1TPa, (e) 1 Pa 9. By what test we can determine whether the polymer is tough or brittle? (a) shear test, (b) creep- test, (c) impact test, (d) flexture test, (e) stress relaxation test. 10. For a polymer with a higher Young's modulus, (a) the hardness is higher, (b) the toughness is higher, (c) the elongation at break is higher, (d) the melting temperature is higher, (e) it is more liquid-like. 11. If a polymer has craze, (a) it is brittle, (b) solvent is used to avoid the craze, (c) the elongation at break is high, (d) the void content in the craze is 9% , ( e) the craze direction is parallel to the stress direction 12. Which one is NOT the characteristic of a ductile polymer? (a) necking, (b) shear band, (e) large area under the stress-strain curve, (d) ABS is ductile, (e) atactic polystyrene is ductile. 13. The glass transition temperature of an amorphous polymer is 120°C. At room temperature, which one is NOT right? (a) it is in glassy state, (b) it is hard, (c) the compliance is low, (d) the elongation is high, (e) there is no long-range chain motion. 14. For a rubber, the elongation to break is about (a) 10%, (b)100%, (c)1000%, (d) 1%, (e) 10000 % 15. For a rubber, which one is NOT true (a) it is incompressible, (b) its T, is very low, (c) its impact strength is high, (d) its elongation is high, (e) ABS is a kind of rubbers. 1. To determine the Tg of polymers, which method is NOT applicable? (a) dilatometry, (b) OM, (e) DSC. (d) HDT. o d ) T0 sho dai n0 nar onom (o) itivo bos ed do o lT ed 2. To determine the Tm of polymers, which method is NOT applicable? (a) POM, (b) WAXD, (c) SEM, (d) DSC. MGT0 2lsbom tods bne M001 To ulubom oY ed mlog 3. To determine the crystallinity, which method is NOT applicable? (a) density, (b) DSC, (c) wide angle X-ray, (d) GPc M1RAY0 s 4. To observe the craze of polymers, we can use (a) DSC, (b) TEM, (c) WAXD, (d) SAXS. ot im A b st 0 5. For PE crystals, which one is NOT right? (a) normally it is orthorhombic, (b) it can form banded 01spherulites, (c) the single lamellar crystal is usually triangle shape, (d) the lamellar thickness is larger at high crystallization temperature, (e) there are five chains in one unit cell. s6 When using TEM to observe lamellar thickness, which one is NOT right? (a) using the diamond knife to cut the sample, (b) ultra-thin films (-50 nm thick) are required, (c) staining is required to enhance the contrast, (d) the magnification factor is -5000X, (e) the v msa im o odqm th of lamellac is -1 olo o r bon 7. To observe spherulites using POM, which one is NOT right? (a) Maltess cross pattern is normally found, (b) POM can distinguish the a-form and B-form of iPP, (c) banded spherulites with ring patterns are always observed, (d) crystal growth rate can be measured, (e) the spherulitic diameter is normally 10 um. 8. The Young's modulus of rubber is about (a) 1GP , (b) 1MPa, (c) 1 kPa, (d) 1TPa, (e) 1 Pa 9. By what test we can determine whether the polymer is tough or brittle? (a) shear test, (b) creep- test, (c) impact test, (d) flexture test, (e) stress relaxation test. 10. For a polymer with a higher Young's modulus, (a) the hardness is higher, (b) the toughness is higher, (c) the elongation at break is higher, (d) the melting temperature is higher, (e) it is more liquid-like. 11. If a polymer has craze, (a) it is brittle, (b) solvent is used to avoid the craze, (c) the elongation at break is high, (d) the void content in the craze is 9% , ( e) the craze direction is parallel to the stress direction 12. Which one is NOT the characteristic of a ductile polymer? (a) necking, (b) shear band, (e) large area under the stress-strain curve, (d) ABS is ductile, (e) atactic polystyrene is ductile. 13. The glass transition temperature of an amorphous polymer is 120°C. At room temperature, which one is NOT right? (a) it is in glassy state, (b) it is hard, (c) the compliance is low, (d) the elongation is high, (e) there is no long-range chain motion. 14. For a rubber, the elongation to break is about (a) 10%, (b)100%, (c)1000%, (d) 1%, (e) 10000 % 15. For a rubber, which one is NOT true (a) it is incompressible, (b) its T, is very low, (c) its impact strength is high, (d) its elongation is high, (e) ABS is a kind of rubbers.

Answer 1

1. d) HDT (Heat Deflection Temperature): Because it used to determine the polymer deformation temperature, not Tg (Transient Temp.)

2. c) SEM (Scanning Electron Microscope): SEM is used to determine the crystal and surface properties of a Polymer, not Tm (Melting Temperature)

3. b) DSC: This is thermo analytical technique, determines the heat required to increase the sample's temperature, rest of techniques determines crystal structures of the polymer.

4. b) TEM (Transmission Electron Microscope): It captures high-resolution of images the surface of the polymer which can be used for crazing of a polymer.