What makes a good insulator

Some of the best ones that you can find around the house like this are Styrofoam those work well because they are so light for all the space it takes up… a lot of air spaces in between the foam and goose down. What are the characteristics of insulation? R-value thermal insulance factor is a measure of thermal resistance.

Polystyrene and plastic foam are both used as insulators as they have small air bubbles trapped inside them. Wool, dry air, plastics, and polystyrene foam are all examples of good insulators. Materials that do not insulate well are called conductors. Conductors have loose bonds that allow particles to move easily and transfer energy from one particle to the next. Plastics and rubber are usually good insulators. It is for this reason that electrical wires are coated to make them more safe to handle.

Metals, on the other hand, usually make good conductors. Aerogel is more expensive, but definitely the best type of insulation. Fiberglass is cheap, but requires careful handling. Mineral wool is effective, but not fire resistant. Cellulose is fire resistant, eco-friendly, and effective, but hard to apply. It must have a very high dielectric strength to withstand the voltage stresses in High Voltage transmission systems. It must possess high Insulation Resistance to prevent leakage current to the earth.

The insulating material must be free from unwanted impurities. It should not be porous. The best thermal insulators have the lowest thermal conductivity; this is the property of a material that measures how well it can conduct heat through its mass. The lower the conductivity measure, the less well a material is able to conduct heat, thus enabling it to trap heat or protect contents from outside heat.

A material that does not easily transmit energy, such as electric current see also current or heat. Keeping the inside of buildings warm and people warm can be done by covering them or any other object in layers of an insulator. Trapping air in layers is a very effective way of insulating an object. Cats fluff up their fur and birds do the same to their feathers when it is cold. This traps air inside the fur or feathers and reduces the amount of heat energy these animals lose.

People wrap themselves in layers of clothes for the same reason. The thicker the layers and the more layers of clothing someone is wearing, the better the insulation. Polystyrene and plastic foam are both used as insulators as they have small air bubbles trapped inside them.

The same idea is used to keep the inside of buildings warm. Insulators like fibreglass and plastic foam are put into the cavity in the walls of a building to trap air and to reduce the transfer of heat energy so that heat stays inside the building. Home Depot sells a variety of insulators that range in R-values from R to R Try using a few in your experiments to see how different materials with different R-values insulate.

Fiberglass, denim insulation, wool, and foam sealant are a few examples to experiment with. Try this experiment that tests different insulators and the effect they have on the temperature of a liquid.

This is the second piece in a four-part Science for Students series. Read part one , and check back next week for part three! He is also involved in a number of engineering and environmental education outreach programs through the school.