Full definition
Resilience in elastomers refers to the material's capacity to return stored elastic energy after experiencing deformation. This characteristic is quantified as a percentage of the energy input that is recovered. The measurement is typically conducted using the Bashore rebound test (ASTM D2632), where a steel plunger is dropped from a predetermined height onto a rubber specimen. The rebound height is measured and expressed as a percentage of the initial drop height, thus providing a clear indication of the material's resilience. High-resilience elastomers include natural rubber (NR) with a resilience of approximately 80%, butadiene rubber (BR) at 85%, and silicone rubber ranging from 55% to 65%. Conversely, low-resilience materials, which are characterized by their high damping properties, include butyl rubber (IIR) with 15-20% resilience, chlorobutyl rubber at 18%, and EPDM rubber showing resilience between 40-55%. Understanding resilience is crucial as it directly correlates with hysteresis; the energy that is not recovered during deformation is dissipated as heat, affecting the performance and longevity of the elastomer in practical applications.
In dynamic applications such as tires, vibration mounts, and belt bodies, high resilience is advantageous because it minimizes heat buildup during operation, thereby extending the service life of the product. Low-resilience materials, on the other hand, are beneficial in damping applications like shock absorbers, engine mounts, and sound insulation where effective energy absorption is critical. The selection of elastomers based on their resilience properties is a vital consideration in design and material selection processes. Furthermore, it is essential to conduct the Bashore rebound test at standard temperature (23°C) as resilience is highly temperature-dependent. This ensures accurate and consistent results, which are critical for quality control of incoming materials in manufacturing processes.