Polymer B is a polymer which melts when heated.
What word is used to describe polymers which melt when heated?
How to approach this question
There are two main classifications for polymers based on their behaviour when heated. One type melts and can be remoulded, while the other type does not melt but chars. What is the name for the type that melts?
Full Answer
Thermoplastic / Thermosoftening
Polymers can be classified based on their structure and response to heat:
- **Thermoplastics (or Thermosoftening polymers):** These polymers consist of long individual chains that are held together by weak intermolecular forces. When heated, there is enough energy to overcome these weak forces, allowing the chains to slide over one another. This causes the polymer to soften and melt. When cooled, the forces reform, and the polymer solidifies. This process is reversible, meaning thermoplastics can be melted and reshaped multiple times. Examples include poly(ethene) and PVC.
- **Thermosetting polymers:** These polymers have strong covalent bonds (cross-links) between the polymer chains. These cross-links hold the chains in a fixed, rigid structure. When heated, there is not enough energy to break these strong covalent bonds. Therefore, thermosetting polymers do not melt; they will char and decompose at very high temperatures. This change is irreversible. Examples include Bakelite and epoxy resins.
Common mistakes
✗ Giving the opposite term, "thermosetting".
✗ Describing the property (e.g., "meltable") instead of giving the specific scientific term.
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