Answer:-

The free radical mechanism is the most common process in addition polymerization, often referred to as a chain reaction, which consists of three distinct steps as follows:

Step 1: Chain Initiation a. The chain reaction initiates through a free radical generated from an initiator (catalyst) like benzoyl peroxide, acetyl peroxide, tert-butyl peroxide, and others. b. As an example, acetyl peroxide can produce a methyl radical, as shown below:

c. The resulting free radical (denoted as “R^•”) attaches itself to the olefin (vinyl monomer), forming a new radical composed of two parts: the attached radical and the monomer unit.

Step 2: Chain Propagation a. The new radical generated during initiation reacts with another molecule of the vinyl monomer, creating a larger radical. b. This larger radical, in turn, reacts with another monomer molecule, and this sequence repeats rapidly. c. This rapid repetition is known as chain propagation and leads to the formation of high molecular mass radicals.

Step 3: Chain Termination a. At some point, the growing chain experiences termination, which can occur through various processes. b. One mode of termination involves the combination of two growing chain radicals.