Phenolic vs other thermosets: formaldehyde condenses with which substrate to produce a non-phenolic resin?

Difficulty: Easy

Correct Answer: Melamine

Explanation:


Introduction / Context:
Condensation of formaldehyde with various nucleophilic substrates yields different thermoset families. Phenolic resins result from phenol-formaldehyde reactions, while melamine-formaldehyde resins constitute a separate class with distinct performance.



Given Data / Assumptions:

  • Phenolic substrates include phenol, resorcinol, and p-substituted phenols like p-cresol.
  • Melamine is a triazine amine, not a phenolic compound.
  • Formaldehyde acts as a crosslinker via methylol formation.



Concept / Approach:
Phenolic resins require phenolic hydroxyl groups. Amino resins (e.g., melamine–formaldehyde) form by condensation at amino groups, producing methylene and methylene-ether linkages typical of MF resins, known for hardness and heat resistance.



Step-by-Step Solution:
List phenolic candidates: phenol, resorcinol, para-cresol.Identify melamine as non-phenolic (amino) substrate.Therefore, melamine with formaldehyde does not produce a phenolic resin.



Verification / Alternative check:
Commercial tabletop laminates and dinnerware often use melamine–formaldehyde, not phenolics, highlighting the different resin family.



Why Other Options Are Wrong:
Phenol/resorcinol/p-cresol all yield phenolic-type networks with formaldehyde.



Common Pitfalls:
Assuming all formaldehyde condensations are “phenolic”; overlooking amino resins as a major thermoset class.



Final Answer:
Melamine

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