Question

Which one among the following is a thermosetting plastic?
A.PVC
B.PVA
C.Bakelite
D.Perspex

Answer 1

Hint: Thermosetting plastics are made up of long chains of molecules that are cross-linked. Basically, they have a very rigid structure. They cannot be reformed or recycled once they are fixed.

Complete step by step answer:
A thermosetting polymer is also known as thermoset or thermosetting plastic. It is basically a polymer which consists of a cross linked structure and heavily branched molecules. These polymers are hardened during the moulding process and they cannot be further remolded or softened after solidifying.
Moreover, one of the most common examples of thermosets is Bakelite which is another name of phenol formaldehyde. Its structure is as shown:
As shown in the above picture, it is made up of phenol and formaldehyde. Moreover, when phenol is taken in excess and the reaction medium is made acidic, then the product of the condensation reaction obtained is also acidic whereas when the quantity of formaldehyde is more, then the reaction will occur in the basic medium.

-Some properties of Bakelite are listed below:
Its moldings are heat and scratch resistant.
Owing to its low electrical conductivity, it is resistant to electric current.
They are also resistant to several destructive solvents.

Hence, option C is correct.

Note:
Since Bakelite has low electrical conductivity and high heat resistance, it can be used in manufacturing electrical switches and machine parts of electrical systems. Moreover, phenolic resins are also used extensively as adhesives and binding agents. They are also used in the coating industries.