Full definition
Chlorosulfonated polyethylene (CSM), commonly known as Hypalon, is a synthetic rubber that excels in environments where weathering and chemical exposure are significant concerns. The unique structure of CSM, characterized by the incorporation of chlorine and sulfonyl groups onto a polyethylene backbone, allows it to exhibit outstanding resistance to ozone, UV radiation, and a wide variety of acids and alkalis. This makes it particularly valuable in industries requiring durable materials that can withstand harsh conditions. The chlorine content, typically ranging between 25-43%, contributes to its color stability, allowing manufacturers to produce vibrant and long-lasting hues suitable for various applications.
With a temperature range of -30 to +120°C, CSM rubber maintains its mechanical properties across a broad spectrum of operating conditions. It typically has a hardness range of 40-90 Shore A, tensile strength of 10-20 MPa, and an impressive elongation capability of 200-500%. These attributes make CSM rubber a preferred choice for applications that demand both flexibility and strength, such as roofing membranes and cable jacketing in demanding environments like nuclear facilities.
However, CSM does have its limitations. It shows poor resistance to aromatic and chlorinated solvents and can exhibit moderate compression set, which may affect its longevity in certain applications. Additionally, while it offers excellent properties, the relatively high cost of CSM has led to a decline in usage as alternatives like EPDM and FKM (fluoroelastomers) have emerged, offering comparable performance at lower prices. Despite this, CSM continues to be utilized in specialized applications where its unique chemical resistance and durability are critical, such as in chemical tank linings and inflatable structures. While DuPont originally marketed CSM under the brand name Hypalon, the production landscape has shifted, with current manufacturers including Tosoh (Exoprene) and Jilin Petrochemical stepping in to fill the gap left by DuPont's exit from the market.