MCQ Detailed View

Polymers can be broadly divided into two types: linear polymers and cross-linked polymers. Linear polymers consist of long chains arranged side by side, while cross-linked polymers contain chemical bonds that connect different chains together, creating a network-like structure. This cross-linking gives the polymer high strength, hardness, and resistance to heat.

Among the given options, Bakelite is the correct example of a cross-linked polymer. It is formed by the condensation reaction of phenol with formaldehyde under controlled conditions. The polymerization produces a highly cross-linked three-dimensional network that is hard, rigid, and insoluble.

Let’s briefly review the other options:

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  Nylon: It is a synthetic polyamide and a linear polymer, not cross-linked.

  
  


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  Polyester: Also a linear polymer, commonly used in fabrics and plastic bottles.

  
  


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  PVC (Polyvinyl chloride): A linear or slightly branched polymer used in pipes and insulation.

  
  

Unlike these, Bakelite has a rigid cross-linked structure, which makes it suitable for making electrical insulators, handles of cooking utensils, switches, and automobile parts. Because of its excellent thermal resistance, Bakelite does not soften on heating and retains its shape, making it a thermosetting plastic.

The importance of cross-linking is that it increases the polymer’s mechanical strength, thermal stability, and chemical resistance. This is why Bakelite was one of the first commercially successful plastics and is still considered a model example of cross-linked polymers.

In conclusion, the correct answer is Bakelite, which represents a cross-linked, thermosetting polymer widely used in household and industrial applications.