Full definition
Polychloroprene (CR) rubber is inherently flame-retardant due to its high chlorine content (~36% by weight), which releases HCl gas upon combustion — a dense, non-flammable gas that suppresses flame propagation by diluting oxygen and quenching free radicals. This inherent flame resistance means CR achieves UL 94 V-0 or V-1 ratings without the addition of flame-retardant additives (though additives like ATH can further enhance performance). Oxygen index (LOI): 26-32% (vs 17-20% for NR/SBR — which are flammable). CR self-extinguishes within seconds of removing the ignition source. Per UL 94, ASTM D635, and ISO 340 (for conveyor belt applications). This property makes neoprene the material of choice for: electrical cable jacketing (NEC types SO/SOW), conveyor belts in underground mines (MSHA approved), fire-resistant gaskets and seals, transit vehicle components (NFPA 130 compliance), and military/aerospace applications requiring non-propagating flame behavior. EPDM, NR, and SBR cannot achieve flame resistance without significant additive loading that compromises mechanical properties.