Melamine is a thermosetting plastic; for it one can say that-
it can be easily remoulded on heating.
A. it cannot resist fire.
B. it has a cross-linked arrangement of molecules.
C. its 'tolerance', towards heat is very much lower than those of other plastics.
D. it can be easily remoulded on heating.
Answers
Thermoplastics can be softened by heat but thermosetting plastics cannot be softened by heat. This is due to the difference in their structure. Both, thermoplastics and thermosetting plastics are made up of long chain molecules called polymers. In thermoplastics, the long polymer chains are not cross-linked with one another [Figure (a)]. Due to this, on heating, the individual polymer chains can slide over one another and thermoplastic material becomes soft and ultimately melts.
On the other hand, in thermosetting plastics, the long polymer chains are cross linked with one another [Figure (b)]. These cross-links prevent the displacement (or sliding) of individual polymer chains on being heated. Due to this, thermosetting plastics do not become soft on heating (or change their shape on heating) once they have been
set into a particular shape.
For example, polythene is a thermoplastic having linear polymer chains with no cross-linkages, so it becomes soft on heating. On the other hand, bakelite is a thermosetting plastic having long polymer chains connected through cross-links (or held strongly through cross-links), due to which it does not become soft on heating.
Answered by | 27th Mar, 2015, 03:34: PM
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Answer:
Melamine is plastic which can tolerate heat better than other plastics and resist fire. It is used for making floor tiles, unbreakable kitchen wares, etc. It is a fire resistant plastic. The uniforms of fire man have coating of melamine plastic to make them fire resistant. Special plastic cook ware made of melamine is used in microwaves oven for cooking food. In microwave ovens, the heat cooks the food buddies not effect the plastic vessel.