Discussion
Phenol-formaldehyde resin is prepared by
Answer: A
Phenol-formaldehyde resin is made by condensation polymerization.
Phenol and formaldehyde react step by step, the methylol groups condensing with phenol rings to form methylene and ether bridges and releasing water at each step. A reaction that links monomers while eliminating a small molecule is a condensation (step-growth) polymerization; it gives the novolac and resol resins behind Bakelite.
Cationic and anionic polymerizations are chain-growth additions across double bonds with no by-product, and ring-opening polymerization needs a cyclic monomer such as a lactam or lactone.
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