Phenol–formaldehyde (Bakelite-type) materials are made via which polymerisation route?

Introduction / Context:Phenol–formaldehyde resins are the earliest commercial thermosets. Knowing their synthesis route explains their crosslinked network structure and performance.

Given Data / Assumptions:

• Phenolic resins form by step-growth reactions between phenolic hydroxyl and aldehyde groups.
• Networks develop during cure, yielding heat-resistant, dimensionally stable parts.
• They are polymers, not monomers or abrasives per se (though filled composites can be abrasive).

Concept / Approach:Phenol reacts with formaldehyde via condensation (step-growth), producing methylene bridges and releasing small molecules during processing/curing stages. This is not vinyl addition polymerisation.

Step-by-Step Solution:Identify functional-group reaction (phenol + aldehyde).Map to condensation/step-growth chemistry.Select “Condensation polymerisation.”

Verification / Alternative check:Processing of resol/novolac systems in industry corroborates step-growth chemistry leading to crosslinked networks.

Why Other Options Are Wrong:Addition polymerisation: not the mechanism here.Monomer/abrasive: misclassification.Anionic living: unrelated to phenolic condensation.

Common Pitfalls:Equating all crosslinked systems with “addition” type curing; phenolics are classic condensations.

Final Answer:Condensation polymerisation