INSULATING MATERIALS: CHARACTERISTICS AND EXAMPLES - TECHNOLOGY - 2025

The insulating materials are those that reduce, resist or completely prevent the passage of any kind of energy as heat or electricity. They serve to protect living beings, food and other objects from the elements and their conditions; like the plastic coating of cables and the walls or ceilings of houses.

In order to perform their function well, these materials mainly need to have a low thermal conductivity that allows them to reduce heat transmission. They must also have a high resistance to very high temperatures that prevent them from melting.

Air permeability is also a very important property of thermal insulators. They must be materials where the air can flow through its pores. Good thermal insulators have a high permeability to air, since this is an insulating substance itself.

This permeability must not allow the passage of vapor or humidity, so as to avoid or minimize the condensation of liquids or corrosion of the materials. The best thermal insulators have very low permeability to vapor and moisture.

The insulating material must be resistant to water, solvents and chemicals; it must be durable and not lose its efficiency in a short time. It must be easy to install, non-flammable, not absorb odors and not attract fungi or vermin.

Examples of thermal insulators

1- Fiberglass

It is one of the most used for its low coefficient of thermal transmission and high resistance. It also works to isolate from electrical and sound currents. It is made by weaving fine filaments of glass polymers to form sticks, sheets or panels.

2- Mineral wool

It can be manufactured from basalt rocks or from the surface residue of molten metal. It is used for its high resistance to fire, but it is advisable to combine it with other materials to obtain a more efficient heat protection.

3- Cellulose

It is one of the most ecological insulating materials on the market. It is made from the recycling of various paper products.

It is a material that can compact enough, which reduces the presence of oxygen between its particles. This property makes it excellent for minimizing fire damage.

4- Polystyrene

It is a very light and waterproof thermoplastic material that is very good as a temperature and sound insulator.

It is used to make molded polyethylene foam blocks or boards. It is flammable, so it is advisable to cover it with other fireproof materials.

5- Polyurethane

It is an insulating foam that contains a gas in its cells, which is of very low conductivity and of great thermal resistance. It can be used in the form of a foamy spray liquid, in rigid foam blocks, or molded into sheets or panels.

6- Perlite

It is a type of inert volcanic rock composed mainly of silica and aluminum but with some impurities that make it absorb moisture.

It is used in small granules to fill tight spaces and holes. It is a good thermal insulator but it works only if it is dry. Its use has been increasingly reduced due to its poisonous quality.

7- Cork

It is probably the oldest insulating material on the market and the most widely used insulator in the refrigeration industry. It is very resistant to compression and difficult to burn. It can only be used below 65 ° C and tends to absorb moisture.

8- Plastic fiber

It is made primarily from recycled polyethylene plastic bottles. The fibers are woven into a stick shape similar to fiberglass.

This insulator is worked with a retardant so that it does not burn so fast, but it can melt when exposed to flames.

9- Airgel

Initially it was a material used by space projects to make tiles resistant to approximately 2000 ° F with very little heat transfer.

It is currently available on the market in flexible sheets called Pyrogel XT. It is one of the most efficient industrial insulators in the world.

10- Vermiculite

Like perlite, it is dangerous to health. It is used in small granules that are thrown between other materials or to fill holes. It was also used to mix with cement to create a lighter, less heat-conducting concrete.

11- Polisocyanurate

Image recovered from ArchiExpo.

It is a thermosetting foamy plastic that contains in its cells a gas of low conductivity and high resistance, free of hydrochlorofluorocarbons. The liquid foam can be adapted to the required surfaces.

12- Cotton

As an insulator, it is combined with plastic fibers and borate to make it resistant to animals and retard their inflammation.

13- Animal wool

It is also treated with borate to resist vermin, fire and mold. It can hold large amounts of water, but prolonged, intermittent exposure to the liquid can dissolve the borate.

14- Straw

Used for over 150 years in bale form to insulate barns and houses from heat. They also serve to absorb sound.

15- Hemp

Material commonly used to make ropes, it is currently used as an insulator like other similar vegetable fibers such as straw or wool.

Examples of electrical insulators

1- Wood

Wood is an electrical insulator, and it is still common to see light poles made of wood. However, it should be noted that it is not insulating as long as the wood is dry, since water (and therefore humidity) are conductors of electricity.

2- Rubber

This material, in addition to being very moldable, flexible and resistant, is perfect to avoid conducting electricity. For example, professionals who work directly with electricity use boots made of rubber to preserve their safety.

3- Ceramic

Ceramic restricts ionic and electronic mobility, therefore it is a non-conductive material of electricity. This makes it ideal for the manufacture of high tension discs.

4- Silicone

This widely used material has, among other capabilities, that of isolating electricity. This makes it ideal for sealing electronic components and fixing components.

5- Aluminum oxide

Because it is a non-conductive material, aluminum oxide is perfect for making temperature or electrical insulators, laser tubes, or sealing rings.

Examples of acoustic insulators

1- Lead

It is the most used material for acoustic insulation due to its value for money. Its density, rigidity or porosity are some of its main strengths.

2- Steel

Steel causes sound to bounce when it hits it, making it a very powerful acoustic insulator. Building doors or panels in bars and leisure centers are usually made of steel to maintain insulation from internal or external sound.

3- Rock wool

It is actually an acoustic absorber, but it is also effective for sound insulation. It is a robust material and widely used in certain structures for being aesthetically attractive.

4- Elastomers

Material used for the construction of houses for its ability to isolate sound, keep heat and prevent cracks or fissures from being generated. It has a high life cycle.

How does heat flow?

Heat will always move from hot areas to cold areas seeking balance. If the inside of a tank protected by thermal insulation is colder than the air outside, the tank will attract outside heat. The more difference in temperature, the faster the heat will flow to the cold area.

Driving

It is the way that energy moves through materials from molecule to molecule. This requires physical contact between the particles and a certain difference in temperature; By placing a spoon in a cup of hot coffee, the heat is conducted from the liquid to the metal and through the handle to the hand.

Convection

It is the way liquids and gases transport heat when they move from one place to another. This is why lighter, warmer air seeks to rise, and cold, dense air tends to seek ground level.

Radiation

It is the transmission of energy directly through a completely transparent medium heating all solid material in its path. This happens, for example, with light such as infrared radiation (a magnifying glass) or with some kind of electromagnetic waves.

References

1. Jessica Ring. What Are Insulators? Recovered from sciencing.com.
2. FAO Corporate Document Repository. Thermal insulation materials, technical characteristics and selection criteria. Fisheries and Aquaculture Department. Recovered from fao.org.
3. ThermaXX Jackets (2011). 5 Most Common Thermal Insulation Materials. Recovered from thermaxxjackets.com.
4. gov. Insulation Materials. Us department of energy - Office of energy efficiency & renewable energy. Retrieved from energy.gov.
5. Loise Kinyanjui. The Properties of Insulators. Sciencing. Recovered from sciencing.com.
6. Insulation materials and their thermal properties. Recovered from greenspec.co.uk.
7. Thermal insulation materials. Connection Magazines. Recovered from build.com.au.