Foam plastic, also known as porous plastic, is a material distinguished by the presence of countless tiny pores within its structure. It is produced from resin as the primary raw material, with a gas phase introduced and trapped during manufacturing to create the characteristic cellular texture.
The properties of foam plastic follow directly from its structure. It is lightweight, because the pores replace solid material with air. It provides thermal insulation, since the trapped air retards heat transfer. It absorbs sound, by softening and scattering sound waves that strike it. It cushions against shock, compressing to absorb impact energy. And it resists corrosion, protecting what it surrounds from chemicals and moisture.
Foam products are divided into soft and hard varieties. Soft foams bend and compress readily, making them useful for cushioning and sealing. Hard foams retain their shape under load, providing structural insulation and rigid packaging. The choice between them depends on the application.
Compared with solid plastic, foam plastic is significantly different in performance. Its density is lower, and its weight is lighter for a given volume. At the same time, its specific strength, strength per unit of weight, is higher, meaning it supports more load for its weight. Strength increases with density, giving manufacturers a way to tune the material to the need.
These characteristics make foam plastic broadly useful. It appears in thermal and acoustic insulation, cushioning packaging, and structural elements such as vehicle panels and hull parts. Its combination of light weight, insulation and shock resistance ensures its continued use wherever those qualities are required.
