How does memory foam remember?
One of the most widely used NASA spin-off inventions, memory foam – also known as ‘temper foam’ and ‘slow spring-back foam’ – was originally designed with aircraft seat safety and protecting astronauts from g-forces and collisions in mind. This special plastic foam has the ability to deform under extreme pressure, absorbing the energy from crashes and providing shock absorbency while also returning to its original shape.
A foam can be a solid or a liquid that contains trapped bubbles of gas inside it. Memory foam is a solid visco-elastic foam – ‘visco’ (as in viscous) means that it moves when you apply pressure, and ‘elastic’ means it returns to its original shape when you remove that pressure. This particular foam is made from open-cell polyurethane, which is a synthetic polymer that features a network of tiny pores or bubbles that shift under pressure, rather than merely compressing. Memory foam responds to changes in temperature and tends to be ﬁrmer when it’s cool but softer when it’s warm. Upon applying pressure, the foam distributes the weight placed on top of it. This material has since been used for many other useful applications, such as mattresses, crash helmets, shoe insoles and even prosthetics.