Question

Which of the following is not true for thermoplastic polymers?
A) Thermoplastics are linear polymers.
B) They often melt on heating.
C) Molten polymer can be remolded into any shape.
D) They have cross-linkage which breaks on heating.

Answer 1

Hint: Thermoplastic polymers do not have cross-linkage which breaks as they usually melt on heating but they have linear or branched structures. Thermosetting polymers have cross-linkage.

Step-by-Step Explanation:
Thermoplastic polymers are the plastic polymers which can be softened and melted by heating but they set again on cooling. They have a linear or branched long chain of molecules. They often melt on heating and become soft. When they are in their molten form, they can be remolded in any shape. Once they are cooled, they set again. This is all true. They do not have cross-linkage and network like structure. Thermosetting polymers are the polymers that have cross-linkage which breaks on heating. Hence, option D is not true. And we are asked which one is not true.

Here the correct option is ‘D’.

Additional Information: Thermosetting polymers are the polymers that have cross-linkage and network like structure. That’s why thermosetting polymers once cooled after heating cannot be remolded in any shape again even when heated. Some facts about thermoplastic polymers-
Thermoplastic polymers due to its softening property are also called thermo-softening polymers.
They are strong, brittle and resistant to chemicals.
Some examples of thermoplastic polymers are- polythene, acrylic, nylon, Teflon, polystyrene, polyvinyl chloride and polypropylene.

Note: Thermoplastics are all around us and are such a part of daily life that we don’t even notice them. Thermoplastic polymers are used in cutlery handles, toilet seats and cisterns. They are used in aircraft and car parts, in packaging and storage materials like packaging film. They are used in insulating foam and carpet and stockings. Thermoplastic polymers are used for manufacture of pipes, ropes, belts, insulators and adhesives