Full definition
Chlorosulfonated polyethylene — a specialty synthetic rubber providing excellent resistance to weathering, ozone, UV radiation, oxidizing chemicals, and a wide range of acids and alkalis. The combination of chlorine (~25-43%) and sulfonyl groups on a polyethylene backbone gives CSM unique color stability (can be made in bright, stable colors) and chemical resistance. Temperature range: -30 to +120°C. Properties: hardness 40-90 Shore A, tensile 10-20 MPa, elongation 200-500%, good abrasion resistance, good electrical insulation. ASTM D2000 classification: BE/CE. Limitations: poor resistance to aromatic and chlorinated solvents, moderate compression set, relatively high cost. Applications: white and colored roofing membranes (20+ year life), power cable jacketing (nuclear industry), chemical tank linings, inflatable structures, coated fabrics, and hose covers. DuPont originally marketed CSM as Hypalon but exited the market; current producers include Tosoh (Exoprene) and Jilin Petrochemical. Usage declining as EPDM and FKM cover most application niches at better price/performance.