Polystyrene and plastic foam are both used as insulators as they have small air bubbles trapped inside them. This makes them very good insulators because heat energy can’t flow through them. The same idea is used to keep the inside of buildings warm.
What Makes a Good Thermal Insulator?
A thermal insulator is a material that reduces the flow of heat. Thermal insulation is the process of creating a barrier between two areas that heat can not easily pass through.
This process can be used to keep an area cool or to prevent heat from escaping. The three main types of thermal insulation are conductive, convective, and radiative.
Conduction is the transfer of heat through a material. The rate of heat transfer is dependent on the conductivity of the material.
The lower the conductivity, the better the material is as a thermal insulator. The most common conductive materials are metals. Metals are good conductors because they have a high number of free electrons.
The free electrons are able to move around and transfer heat. Convection is the transfer of heat through the movement of fluids.
The most common fluid is air. Air is a poor conductor of heat because the molecules are spread out. The molecules can only transfer heat by bumping into each other.
This is why hot air rises and cold air sinks. The third type of heat transfer is radiation. Radiation is the transfer of heat through electromagnetic waves.
The most common type of radiation is infrared radiation. Infrared radiation is invisible to the human eye but can be felt as heat.