Introduction to Foams
What is a solid foam?
Solid foams are cellular materials, i.e. materials which are made up from a framework of solid material surrounding gas-filled voids (bubbles). Solid foams can be 100 times lighter than the equivalent solid material.
Natural solid foams include wood, bone and sea sponges. The bee's honeycomb is a two-dimensional cellular structure:
Recent developments in metal foams, especially aluminium, have produced a new class of lightweight materials, which are excellent energy absorbers. This property is useful in reducing the impact of a car crash.
Other applications of solid foams include:
- Cushioning materials in furniture.
- Structural materials such as sandwich board.
- Insulating materials, such as cavity wall insulation.
- Packaging materials, such as expanded polystyrene.
- Several food items, such as bread, cake and other snack foods.