Author(s) :

Jiseok Kim.

Volume/Issue :

Abstract :

Impact absorbing materials are used in many different, industrially relevant areas, from sports to military and defense. This review aims to address the impact absorption of two categories of materials: colloidal and non-colloidal materials. Some model systems are considered: first is Oobleck (corn starch and water), a well-known colloidal system that absorbs shock through shear-induced jamming via frictional particle contacts. Second is dry cornmeal, a granular system which absorbs impact energy through compression and friction under adequate confinement conditions. Lastly, a polymeric system comprising polyborosiloxane (PBS), which absorbs impact through rate-dependent viscoelastic stiffening governed by the Deborah number and temperature-dependent bond dynamics. This review compares the shock absorbing mechanisms and performance of each of these chemically unique systems and aims to provide criteria for selecting the suitable material for a specific application. In addition to mapping mechanisms, practical selection rules are outlined, including when to prefer reversible stiffening (colloids and polymers) versus irreversible compaction (granular solids), how thickness requirements and mass penalties scale with protection level, and what environmental limits (temperature, humidity) matter in field applications.