Step 1: Understanding the Concept:
Polymerization reactions are generally classified into addition (chain-growth) polymerization and condensation (step-growth) polymerization. Addition polymerization of alkenes or vinyl monomers often requires a free radical initiator, such as an organic peroxide (e.g., benzoyl peroxide).
Step 2: Key Formula or Approach:
Determine the type of polymerization for each given polymer. Polymers formed by free radical addition polymerization are the ones that require a peroxide initiator.
Step 3: Detailed Explanation:
Let's evaluate the polymerization process for each option:
- (A) Nylon 6,6 is a polyamide formed by condensation polymerization of adipic acid and hexamethylenediamine. It does not require a free radical initiator.
- (B) Polyacrylonitrile (PAN) is formed by the addition polymerization of acrylonitrile (\(\text{CH}_2\text{=CH-CN}\)). This process typically proceeds via a free radical mechanism, which is initiated by a peroxide catalyst.
- (C) Terylene (Dacron) is a polyester formed by condensation polymerization of ethylene glycol and terephthalic acid. It does not use a peroxide initiator.
- (D) Bakelite is a thermosetting polymer formed by the condensation reaction of phenol with formaldehyde. It is catalyzed by either acid or base, not a peroxide initiator.
Step 4: Final Answer:
Polyacrylonitrile requires a peroxide initiator.