Emulsion polymerisation of vinyl chloride for PVC: what is the typical reactor temperature maintained (°C) during production?

Introduction / Context:
Poly(vinyl chloride) (PVC) can be produced by suspension or emulsion polymerisation. Reactor temperature control directly affects polymerisation rate, particle size, molecular weight, and safety. This question targets the typical temperature used in emulsion processes.

Given Data / Assumptions:

• Water-based emulsion polymerisation with surfactants and free-radical initiators.
• Safety constraints due to vinyl chloride monomer volatility.
• Desire for controlled molecular weight distribution.

Concept / Approach:
Emulsion polymerisation of VCM commonly operates in the moderate temperature range around 40–60 °C; a typical nominal setpoint is roughly 50 °C. This balances initiator decomposition, conversion rate, and heat removal while avoiding excessive chain transfer and runaway risk.

Step-by-Step Solution:
Identify feasible thermal window for initiators used in emulsion PVC.Select a mid-range value (≈50 °C) consistent with practice.Rule out extreme temperatures that would be unsafe or chemically inappropriate.

Verification / Alternative check:
Process descriptions and safety guidelines specify polymerisation typically in the 40–60 °C range, with jacketed vessels and staged initiator feeds.

Why Other Options Are Wrong:
−20 °C: impractically low for initiator kinetics.250–500 °C: decomposition and runaway; not applicable to aqueous emulsion systems.95 °C: high for standard PVC emulsion processes and risks undesirable side reactions.

Common Pitfalls:
Confusing suspension versus emulsion conditions; assuming higher temperature always improves throughput without considering quality and safety.

Final Answer:
50 °C