Full definition
Polychloroprene (CR) provides inherent and superior ozone resistance compared to unsaturated rubbers (NR, SBR, NBR) due to its low residual unsaturation — the chlorine-substituted double bond is far less reactive with ozone (O₃) than the unsubstituted double bonds in diene rubbers. While NR and SBR develop surface cracks perpendicular to the stress direction after just hours of ozone exposure (as low as 25 ppb), CR maintains surface integrity for years of outdoor exposure without antiozonant additives. Testing: per ASTM D1149 (ozone chamber test at 40°C, 50 pphm O₃ concentration, specimen under 20% strain) — CR shows no cracking after 100+ hours, while NR/SBR crack within 4-24 hours without protection. This inherent ozone resistance, combined with good UV and weather stability, makes neoprene the preferred material for: outdoor seals and gaskets, expansion joints, bridge bearing pads, cable jackets, marine applications, and any rubber product with sustained outdoor exposure. Only EPDM, silicone, and fluoroelastomers match or exceed CR's ozone resistance. Per ASTM D1171 for outdoor weathering and D1149 for ozone chamber testing.