When a material is deformed, a certain amount of energy is required to achieve deformation. Recovery from deformation also takes a certain amount of energy. For polyurethanes, the ratio of energy returned during recovery to the energy required to cause the deformation is called polyurethane resilience.

A material that is perfectly elastic will return all the energy during recovery. A more viscous material will return less energy upon recovery because some of the input energy was lost in the form of heat. The energy loss is due to internal friction within the elastomer and is called Hysteresis; it’s equal to the per cent energy loss per cycle. A material with high resilience will be very lively, think bouncy ball because all the energy that is input during deflection is returned on the rebound. A material with low resilience will feel dead because the input energy is lost in the form of heat during deflection.

Polyurethane resilience is typically measured in a variety of ways with the most common probably being the Bashore Rebound Test. Resilience is measured on a scale of 0 to 100%. A 100% resilient material would return all of the input energy upon recovery.

Shown here are tables containing the polyurethane resilience for a variety of Gallagher Corporation compounds. Resilience is a property that can vary widely among the compounds independent of the hardness. Polyurethane resilience will also vary widely based on the temperature of the material. When a polyurethane part is heated, it’s able to flow more easily, thus reducing the internal friction and increasing the resilience.

Feel free to contact us for more information on this and other topics or to discuss your specific application.

Bashore Resilience Summary Tables

Hardness Rebound
GC 485-3 85A 25%
GC 855 55A 33%
GC 960 60A 30%
GC 970 70A 35%
GC 980 80A 30%
GC 990 90A 30%
GC 995 95A 28%
GC 1260 60A 60%
GC 1265 65A 60%
GC 1270 70A 60%
GC 1275 75A 60%
GC 1280 80A 60%
GC 1285 85A 60%
GC 1290 90A 45%
GC 1295 94A 60%
GC 1080 80A 60%
GC 1085 85A 50%
GC 1090 90A 45%
GC 1095 95A 40%
GC 1550 50D 40%
GC 1555 55D 41%
GC 1560 60D 42%
GC 1565 65D 46%
GC 1575 70D 50%