This is usually done by spreading the deceleration of the impacting object over a longer period of time. The graphic below shows load versus time for a silica aerogels sample, and two other materials. The plots show that both the aerogel and the polystyrene foam reduce the maximum load produced to a very low level. It may, therefore, seem that readily available polystyrene foam may be a more appropriate material than the more unusual silica aerogel. The situation is not as straightforward as this.
Many organic foams produce a significant amount of rebound when they are impacted.
This rebound effect can often do further damage to the object being protected. This is an important phenomenon to consider when developing materials for safety and protective devices. The production and use of silica aerogels is environmentally benign. No significantly hazardous wastes are produced during their production. The disposal of silica aerogels is perfectly natural.