Materials scienceLesson 1 of 2 in the course Polymers

Polymer Structure, Synthesis, Properties, and Applications

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Polymers are materials made of very large molecules built from repeating subunits. They appear in living organisms, household products, clothing, construction materials, and many technologies. This lesson introduces polymer terminology, major types, and the development of the modern concept of polymers.

A polymer is a substance whose molecules, called macromolecules, consist of many repeating subunits derived from one or more kinds of small molecule called monomers. The process that links monomers into polymers is called polymerization.

All flashcards

What is a repeat unit in a polymer?
The portion of a monomer incorporated into the polymer structure; it may not retain every atom of the starting monomer.
What is polymer dispersity?
The ratio of weight-average to number-average molecular weight, Mw/MnM_w/M_n, describing the breadth of a sample’s molecular-weight distribution.
How does dense cross-linking affect polymer structure?
It joins chains into a rigid network called a thermoset.
What is reptation in polymer physics?
The constrained, snakelike motion of an entangled polymer chain through a virtual tube.
What can differential scanning calorimetry measure in polymers?
Thermal events such as glass transition, crystallization, and melting.

Quiz questions

  1. In chain polymerization, how are monomers added to a growing polymer?Answer: One at a time to an active chain.
  2. What distinguishes polycondensation from polyaddition?Answer: Polycondensation releases a low-molar-mass by-product at each reaction step.
  3. What describes a semicrystalline polymer’s morphology?Answer: Ordered crystalline regions coexist with disordered amorphous regions.
  4. Which statement correctly distinguishes glass transition from melting in polymers?Answer: Amorphous polymers undergo glass transition but lack a crystalline melting transition.
  5. Which technique can measure polymer molecular-weight averages and dispersity?Answer: Size-exclusion chromatography.

Based on the Wikipedia article Polymer, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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