Module 9: Thermal Transitions

9.0 Introduction & Study Guide

In this short module, we are going to learn a lot in a short time! We will learn about thermal transitions that occur in polymers, specifically the melting temperature, the crystallization temperature, and the glass transition temperature. We will focus on how structure impacts these temperatures, so given the repeat units of two polymers you will be able to predict which has the higher or lower Tg or Tm. Chapter 11 in the Polymer Science and Engineering eBook goes into more detail than we will. Instead of starting with a chapter reading, watch the lecture and use the reading to supplement and/or clarify the lecture. If content is not in the Study Guide, you are not responsible for it.

Use Chapter 11: Structure and Morphology of the Polymer Science and Engineering eBook (or the equivalent in a print version) as a reference for studying the content covered in the lecture. The textbook goes into much greater depth than we will. Use the study guide, lecture, and lecture notes as your primary materials and the chapter as a supplement.

Study Guide for Module 9: Thermal Transitions

By the end of the module, can you do the following?

  1. Define and explain the following as they relate to polymers:
    1. Crystallization temperature, Tc
    2. Melting temperature, Tm
    3. Glass transition temperature, Tg
    4. Free volume
  2. Briefly explain why the melting and crystallization temperatures are usually not the same temperature for polymers.
  3. Briefly explain why polymers often melt over a range of temperatures.
  4. Given a specific volume versus temperature plot, identify (if present):
    1. The melting/crystallization transition
    2. The glass transition
  5. Define under cooling (super cooling) as it relates to polymer crystallization and explain its importance.
  6. Define annealing as it relates to polymer crystallization and explain its importance.
  7. Explain how the following affect the melting temperature of a polymer:
    1. Stiffness of the polymer backbone
    2. Molecular interactions
    3. Bulky side groups
    4. Diluents (e.g., solvents)
    5. Co-monomers
    6. Molecular weight
  8. Given a series of polymers (with the structures provided), order them by increasing (or decreasing) melting temperature.
  9. Determine which polymer (structures given) has the higher melting temperature and explain how they came to that conclusion in one to two sentences.
  10. Explain how the following affect the glass transition temperature of a polymer:
    1. Stiffness of the polymer backbone
    2. Molecular interactions
    3. Bulky side groups
    4. Flexible side groups
    5. Diluents (e.g., solvents, plasticizers)
    6. Molecular weight
    7. Degree of cross-linking
    8. Degree of crystallinity
    9. Free volume
  11. Given a series of polymers (with the structures provided), order them by increasing (or decreasing) glass transition temperature.
  12. Determine which polymer (structures given) has the higher glass transition temperature and explain how they came to that conclusion in one to two sentences.
  13. Describe an amorphous polymer when it is:
    1. Above its Tg
    2. Below its Tg (This was also covered in Module 01.)
  14. Describe a semi-crystalline polymer when it is:
    1. Above its Tm and Tg
    2. Between its Tm and Tg
    3. Below its Tm and Tg (This was also covered in Module 01.)

Get your own copy of the Module 09 Study Guide and Checklist (link goes to a “force copy” Google Doc).

 

License

Polymer Science & Engineering: An Interactive Introduction Copyright © 2023 by Wendy E. Krause. All Rights Reserved.

Share This Book