ASTM D1418 designations

A generalized chemical structure for CPE is shown (Figure 8.1). The ASTM D1418 designation for CPE is CM where C denotes chloro and M denotes a saturated chain of the polymethylene type. CPE and CM are often used interchangeably in the industry. In this chapter, the term CPE is used. 

Commercially available fluorocarbon elastomers meet automotive specifications in the HK section of ASTM D2000 and SAE J-200. ASTM D1418 specifies designations of composition, eg, fluorocarbon elastomers are designated CEM, EKM, or EEKM. Commercially available fluorocarbon elastomers offer a balance of those properties needed to meet the major O-ring specifications, such as AMS 7276, AMS 7280A, AMS 7259, MIL 83248 Amendment 1 Type II, Class I and II. 

Currently, seven major manufacturers produce fluorocarbon elastomers, and these are listed in Table 5.1. The main commercially available fluorocarbon elastomers are listed in Table 5.2. In the ASTM D1418, fluorocarbon elastomers have a designation FKM, and in the International Organization of Standardization (ISO) R1629 their designation is FPM. Current worldwide fluoroelastomer demand is 21,000 metric tons, with average annual growth of approximately 7% [5]. 

An alternating copolymer of TFE and propylene (TEE/P) and a terpolymer TFE/P/VDF are fluorocarbon elastomers commercially available under the trademark APE AS. They are characterized by improved low-temperature and electrical properties and steam resistance when compared with FKM and are comparable to PPKM in chemical resistance at lower cost (details in next section). TFE/P has the ASTM D1418 and the ISO 1629 designations FEPM, and in ASTM D2000/SAE J200 it is classified as Type/Class HK. 

Designation ASTM D1418 CO, ECO PO SBS Hytrel (Du Pont trade name) PVC PE... 

Commercially available fluorocarbon elastomers meet automotive specifications in the HK section of ASTM D2000 and SAE J200. ASTM D1418 specifies designations of composition fiuorocarbon elastomers are designated FKM, FEPM, or FFKM in the case of perfiuoroelastomers. 

In addition to natural rubber, today many synthetic rubbers are commercially available. Although there are several ways to classify these rubbers, the American Society for Testing and Materials (ASTM) Standard D1418-85 gives the classification and designation of rubbers based on their chemical composition. Therefore, in this chapter, the classification and naming of rubbers are based on this standard. For convenience, the nomenclature is reproduced in Table 1, extracted from the standard. 

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