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Technical Paper

Performance Studies of Ethylene-Propylene Rubber Automotive Coolant Hoses

1990-02-01
900576
Ethylene-propylene rubber compounds have been utilized in automotive coolant hoses for more than twenty-five years. Throughout this period, hose compositions have continually evolved to meet ever changing requirements of long-term serviceability, higher heat resistance, coolant fluid compatibility, and non-bloom features for the cover. Despite the commercialization of compounds with improved quality and consistency, radiator and heater hoses in certain vehicle models and designs develop cracks well before their expected service life capability. While all hoses including these failures are being exposed to higher levels of heat duress, physical property deterioration, via the usual auto-oxidation mechanism, does not alone seem to be the major cause. This paper describes the nature of coolant hose cracking failures and laboratory studies to explain the observed striae, dendritic structures, and coolant exudation within the hose.
Technical Paper

Meeting Coolant Hose Compound Requirements of the Future

1987-02-01
870190
Ethylene-propylene rubber compounds have been utilized in automotive radiator and heater hoses for many years. This is due to the elastomer having superior resistance to ethylene glycol coolant fluids, outstanding ozone resistance, and excellent heat aging characteristics. However, recent automotive-design and engineering trends have created severe temperature environment under the hood. As a result, EPDM compounds are now evolving to more polymer-rich compositions with increased heat resistance, lower compression set, and non-bloom properties. Compounding principles are described to meet future heat aging requirements of coolant hose. Compositional and structural factors of the polymer are shown to have an important influence in maximizing the heat resistance.
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