A thermosetting plastic differs from a thermoplastic in that a thermosetting plastic
Correct answer: D. sets permanently on first heating because cross links form between the chains
- A. softens every time it is heated and can be remoulded
- B. dissolves readily in water
- C. conducts electricity
- D. sets permanently on first heating because cross links form between the chains
Explanation
Covalent cross links lock the chains into a rigid three dimensional network, so the material cannot be softened and remoulded and simply chars if heated strongly, which is why bakelite is used for electrical fittings and pan handles. A thermoplastic such as polythene has separate chains held only by weak forces, so it softens repeatedly on heating and can be recycled. This difference decides how each plastic is processed and whether it can be recycled.
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About Polymers
Polymers are large molecules made from repeating monomer units joined by covalent bonds. The topic distinguishes addition polymers such as polyethylene, PVC and polystyrene from condensation polymers such as nylon and polyester, and relates chain structure to thermoplastics, thermosetting polymers, elastomers, properties, uses and environmental concerns.
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