Chemistry Reference
In-Depth Information
Section 2.2.2
1. Explain the phenomenon of elasticity.
2. What natural structural arrangement of polymeric chains leads to rubber elasticity.
3. What is meant by the negative coefficient of expansion?
Section 2.2.2.1
1. Write the equation for the reactive force of an elastomer and explain what each term represents and
define an ideal elastomer.
2. What is the entropy of elasticity? What is it proportional to?
3. What is the relationship between the retractive force of an elastomer and its temperature?
4. Write the equation for the work done in stretching a chain of an ideal elastomer and explain what
each term represents.
5. Write the equation for a free energy change of a stretched elastomer.
6. Write the equation for the average energy per (stretched) chain
7. What is the free energy change for a stretched elastomer? Explain.
Section 2.2.2.2
1. Define a Newtonian liquid and a Hookian ideal elastic solid, and an ideal elastomer.
2. What is meant by viscoelasticity?
3. Explain what is meant by a yield point and a Bingham Newtonian fluid.
4. How is the viscosity of a molten polymer related to its temperature?
5. How is shear stress defined mathematically?
6. What is a thixotropic liquid?
7. What is the relationship Newtonian viscosity of amorphous polymers and their chain length?
8. What is shear creep compliance equal to ?
9. Why are shear thinning and thixotropy two different phenomena? Explain
10. What relationship describes flow behavior of liquids that deviate from Newtonian flow?
11. Write the equation for shear-stress-relaxation modulus for viscous fluids. Explain
12. What are the two important quantities in behavior of polymeric liquids?
13. Describe two techniques for measuring the viscosity of molten polymers.
Section 2.3
1. How does crystallinity of polymers that are formed from the melt differ from that of small
molecules?
2. What are the two ways that crystal growth can take place in polymeric materials?
3. What type of polymers tend to crystallize?
4. What is the typical size of polymeric crystals formed from the melt?
5. What is a fringed micelle or a fringed crystallite model?
6. What is the folded chain lamella? An adjacent-reentry model? A switchboard or a nonadjacent-
reentry model?
7. What is drawn fibrilar morphology? What is vitrification?
