Soft materials that absorb impact

Abstract

Hydrogels are networks of polymer chains that are swollen in water. These gels can protect vulnerable objects (e.g., an egg or a fruit) if wrapped there around. Gels are constructed by either physical cross-linking (e.g., gelatin) or chemical cross-linking (e.g., acrylamide). The addition of starch granules to the above gels greatly enhances their protective abilities. When a load strikes a gelatin gel containing 20% starch, the peak impact force is reduced by 25% when compared to a bare gel without the starch. Correspondingly, the coefficient of restitution (COR) is also lowered by the presence of starch (e.g., a ball bounces less on a starch-bearing gel). The impact-absorbing effects of starch granules are correlated to their ability to shear-thicken water. When starch granules are gelatinized by heat, they no longer give rise to shear-thickening, and in turn, their protective ability in a gel is also eliminated.

Dependencies are inferred from the claim text.