Industrial production of nylon-6 from caprolactam: Caprolactam is polymerized to nylon-6 via ring-opening polymerization. At approximately what reactor temperature range is about 90% conversion typically achieved?

Introduction / Context:
Nylon-6 is produced by ring-opening polymerization of ε-caprolactam, often with a small amount of water as initiator. The process requires elevated temperature to drive ring opening and condensation, yielding high molecular weight polymer.

Given Data / Assumptions:

• Reactant: ε-caprolactam.
• Target: ≈90% monomer conversion in the reactor stage.
• We consider typical industrial conditions.

Concept / Approach:
Caprolactam polymerization is thermally activated and commonly carried out around 250–280 °C. Lower temperatures (ambient or below) are far too low for practical rates; excessively high temperatures risk degradation and side reactions, not higher conversions.

Step-by-Step Solution:
Recall standard nylon-6 process: melt polymerization with water initiator.Match typical process window: roughly 250–280 °C.Select the range consistent with ≈90% monomer conversion in reactor.

Verification / Alternative check:
Process descriptions and plant practice reference reactor temperatures near 260–270 °C, followed by finishing/devolatilization to drive conversion and remove residual monomer.

Why Other Options Are Wrong:

• Sub-ambient or ambient ranges (−5 °C, 10–30 °C): kinetics are negligible.
• 500–600 °C: far beyond safe processing; thermal degradation dominates.

Common Pitfalls:

• Mixing nylon-6 (from caprolactam) with nylon-66 (hexamethylene diamine + adipic acid); conditions differ.
• Assuming higher temperature always improves conversion—degradation limits apply.

Final Answer:
250–280 °C