CUET Preparation Today
Case: Read the passage and answer the following questions There are two broad types of polymerisation reactions, i.e., the addition or chain growth polymerisation and condensation or step-growth polymerisation. In chain-growth polymerisation, the molecules of the same monomer or different monomers add together on a large scale to form a polymer. This type of polymerisation is explained free radicle mechanism. Some important addition polymers are polythene and teflon. Condensation polymerisation or step-growth polymerisation generally involves a repetitive condensation reaction between two bi-functional or trifunctional monomeric units. Some important condensation polymers are nylon, Bakelite, and formaldehyde polymer. Copolymerisation is a polymerisation reaction in which a mixture of more than one monomeric species is allowed to polymerise and form a copolymer. Rubber and its derivatives are copolymers. |
| What is the step called in the process of addition of phenyl free radical formed by the peroxide to the ethene double bond thus generating a new and larger free radical? |
Starting step Chain initiation step Chain propagation step Chain termination step |
| Chain initiation step |
| The polymerisation of ethene to polythene consists of heating or exposing to light a mixture of ethene with a small amount of benzoyl peroxide initiator. The process starts with the addition of phenyl free radical formed by the peroxide to the ethene double bond thus generating a new and larger free radical. This step is called the chain initiating step. |
