Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

DoITPoMS Teaching & Learning Packages The Glass Transition in Polymers Questions
The Glass Transition in Polymers AimsIntroductionTheory 1Theory 2 - kinetics vs thermodynamicsMeasurement of TgDemonstrationsSummaryQuestionsGoing further
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Questions

  1. Explain why cooling a liquid very fast (quenching) can lead to the formation of a glass. Your answer should use what you have learnt about the kinetics of glass formation.

  2. What is meant by the 'free volume' of a polymer?

  3. What is the significance of the theoretical 'Kauzmann temperature'?

  4. Why is the measured value of Tg dependent on the method of measurement?

  5. Using what you understand about the way polymer chains behave above and below Tg, why do you think glasses tend to be brittle whereas rubbers are not?

  6. What is meant by the conformation of a polymer? Using a Newman projection show what is meant by the 'trans' and 'gauche' states.

  7. Explain how the dielectric constant of a polymer is affected by the transition to the glassy state.

  8. Explain why the glass transition temperature is strain-rate dependent.

  9. Below and above the Tg of a rubber ball it will rebound after impact. At Tg the ball will not rebound very much at all. Explain how the ball bounces in these three cases from an energetic point of view.

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