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I. 1. Low density and high fill factor: EPDM is a type of rubber with a relatively low density, at 0.87. Furthermore, the ability to add large amounts of oil and fillers allows for a reduction in the cost of rubber products, compensating for the high price of EPDM raw material. Moreover, for EPDM with a high Mooney value, the decrease in physical and mechanical properties is not significant after high levels of filling are used. 2. Aging resistance: EPDM rubber exhibits excellent resistance to weathering, ozone, heat, acids and alkalis, water vapor, color stability, electrical properties, oil absorption, and flowability at room temperature. Ethylene-propylene rubber products can be used for extended periods at 120°C, and can be used for short periods or intermittently at 150–200°C. Adding appropriate anti-aging agents can increase its operating temperature. Peroxide-crosslinked EPDM can be used under harsh conditions. EPDM can remain crack-free for over 150 hours under conditions of an ozone concentration of 50 pphm and a 30% strain. 3. Corrosion resistance: Due to the lack of polarity and low degree of unsaturation in EPDM, it exhibits good resistance to various polar chemicals such as alcohols, acids, bases, oxidizers, refrigerants, detergents, animal and vegetable oils, and waxes ； However, it has poor stability in aliphatic and aromatic solvents (such as gasoline, benzene, etc.) as well as mineral oils. Performance also declines under the long-term effect of concentrated acids. ISO/TO 7620 compiles data on the effects of nearly 400 corrosive gaseous and liquid chemicals on various rubber properties, and specifies grades 1–4 to indicate the degree of these effects, as shown in Table 1. Table 1 Effect of corrosive chemicals on rubber properties. Grade, Volume swelling rate/%, Hardness reduction value, Impact on properties: 1: ＜10, ＜10 – Mild or no effect; 2: 10–20, ＜20 – Slight effect; 3: 30–60, ＜30 – Moderate effect; 4: ＞60, ＞30 – Severe effect. 4. Resistance to water vapor: EPDM exhibits excellent resistance to water vapor, and this property is even better than its heat resistance. In superheated steam at 230°C, there was no change in appearance after nearly 100 hours. Under the same conditions, fluororubber, silicone rubber, fluorosilicone rubber, butyl rubber, nitrile rubber, and natural rubber experience significant visual degradation after a shorter period of time. 5. Resistance to hot water: EPDM also exhibits good resistance to hot water, but this property is closely related to the vulcanization system used. EPDM using dithioldi**rine and TMTD as the vulcanization systems showed very little change in mechanical properties after being immersed in superheated water at 125°C for 15 months, with a volume expansion rate of only 0.3%. 6. Electrical properties: EPDM possesses excellent electrical insulation properties and corona resistance, with electrical performance that is superior to or comparable to that of SBR, chlorosulfonated polyethylene, polyethylene, and cross-linked polyethylene. 7. Elasticity: Due to the absence of polar substituents in the molecular structure of EPDM, its intermolecular cohesive energy is low, allowing the molecular chains to remain flexible over a wide range; this property is second only to that of natural rubber and cis-polybutadiene, and it is maintained even at low temperatures. 8. Adhesiveness: Due to the lack of active functional groups in its molecular structure, EPDM has low cohesive energy; furthermore, the rubber compound tends to frost over, resulting in poor self-adhesion and inter-adhesion properties. II. Modified grades of ethylene-propylene rubber: Since ethylene-propylene terpolymer and EPDM were developed in the late 1950s and early 1960s, various modified ethylene-propylene rubbers and thermoplastic ethylene-propylene rubbers (such as EPDM/PE) have emerged worldwide, providing a wide range of grades for the widespread use of ethylene-propylene rubber. Modified EPDM mainly involves the bromination, chlorination, sulfonation, maleic anhydride treatment, fumaric anhydride treatment, silicone modification, nylon modification, etc. of EPDM. Ethylene-propylene rubber also has acrylonitrile, acrylate, and other grafts. Over the years, many polymer materials with excellent comprehensive properties have been developed through methods such as blending, copolymerization, filling, grafting, reinforcement, and molecular compounding. Through modification, EPDM has also seen significant improvements in its properties, thereby expanding its range of applications. Ethylene propylene rubber bromide is produced on an open mill using a brominating agent. Bromination of EPDM can increase its vulcanization speed and adhesion properties, but it reduces mechanical strength; therefore, brominated EPDM is only suitable as an intermediate layer for bonding EPDM to other rubbers. Ethylene propylene rubber chloride is produced by passing chlorine gas through an ethylene propylene diene monomer solution. Chlorination of EPDM can increase the vulcanization speed as well as its compatibility with unsaturated compounds; its flame resistance, oil resistance, and adhesion properties are also improved. Sulfonated EPDM is obtained by dissolving ethylene-propylene terpolymer in a solvent and then treating it with sulfonating agents and neutralizing agents. Sulfonated EPDM, due to its thermoplastic elastomer properties and excellent adhesion, will find wide application in adhesives, coated fabrics, building waterproofing materials, and anti-corrosion linings. Acrylonitrile-grafted EPDM was prepared by grafting acrylonitrile onto EPDM at 80°C using toluene as a solvent and benzyl perchlorate as an initiator. Acrylonitrile-modified EPDM not only retains the corrosion resistance of EPDM but also achieves oil resistance comparable to that of NBR-26, possessing good physical and mechanical properties as well as processability. Thermoplastic EPDM (EPDM/PP) is obtained by blending ethylene-propylene-diene monomer rubber as the main component with polypropylene. A product that simultaneously achieves the desired degree of crosslinking in EPDM. It not only retains the inherent properties of EPDM in terms of performance, but also possesses significant processability as a thermoplastic, suitable for injection molding, extrusion, blow molding, and calendering. In addition, modified EPDM also includes chlorosulfonated EPDM and acrylate-grafted EPDM.