Type of Seal materials: Which are safe and not?

When having a discussion about seal materials, it is useful to know what they are made out of and how they work. This will help you understand their uses and limitations. They are being used in a variety of fields from food packaging to auto manufacturing.

In general, the function of sealant is to establish a barrier between two objects that need to be kept apart for one reason or another. It usually seals against air or liquids, but it can also block out solids. They are materials that have a low resistance to flow, which means they have a lower viscosity than fluids.    

They are being used in situations where mechanical fasteners cannot provide enough or any sealing ability. This can be attributed to corrosion, vibrations, environmental hazards, or the need for other types of adhesives. Also, due to the nature of sealants, it can be difficult to detect them.

This article will look at some common materials used for seals, their advantages and disadvantages with respect to handling them safely.

PTFE

PTFE, or polytetrafluoroethylene, is a polymer resin. It is basically a large molecule made up of smaller molecules. This material has two very unique properties. The first one is that it does not stick to anything. In fact, it takes an enormous amount of force to tear off PTFE from whatever it is adhered to. The second property is that whatever force does not tear it off also makes it very slippery making PTFE one of the slipperiest substances known to mankind.

As a result, this material is not well suited for seals that will be under pressure or strain as they will easily dislodge and cause leaks. However, it has many useful applications where its lack of adhesiveness is an advantage or where the sealing material will not be under any pressure. These include lubrication, gaskets, and protective covers.

In order to make a seal out of PTFE, it needs to be combined with another polymer resin which will make a thicker/ stiffer material. The most commonly used blend is a 50/50 mix of PTFE and FEP, which has properties very similar to PTFE with the addition of being able to withstand high temperatures (up to 250°C).

Silicone Rubber 

Silicone rubber is one of the most widely used sealant materials in many varieties. It is made up of silicon and carbon atoms. Silicone rubber has a high resistance to heat, which makes it one of the best choices for sealing applications where temperatures are high. It is chemically inert towards most materials, but some types can be attacked by strong acids or amines.

Silicone rubber is used primarily for gaskets and seals that need high-temperature protection. Some of the most common applications are in ovens or around furnaces, but they can also be found in many consumer goods such as hair dryers. This material comes in 2 main varieties: 100% silicone rubber and silicone rubber blended with other materials.

PVB

PVB or Polyvinylidene fluoride is a polymer resin that is similar to PTFE in its properties and application. However, PVB can be manufactured under high pressure making it a lot cheaper than PTFE. It also has a higher resistance to chemicals compared to PTFE which makes it a more durable and longer-lasting sealing material.

One of the main weaknesses is that it cannot be used with high-temperature applications as its melting point is significantly lower than that for PTFE or FEP. It also needs to be applied under pressure, but this can be done manually as well as with an oven or heat press which makes it very useful in the manufacturing process.

Condensation cured silicone is a newer type of sealant material that is similar to 100% silicone rubber because it has the same properties and applications: high-temperature resistance, chemical inertness, and low outgassing. The difference between this and 100% silicone rubber is that condensation cured silicone has a higher outgassing rate. This makes it a better candidate for devices that have sensitive electronics because, unlike 100% silicone rubber, no gasses will be released during operation.

Most other types of sealants are either organic or inorganic and they all have varying degrees of properties making them more suitable for specific applications. The common theme is that they are all very durable and resilient to heat and chemicals. It is important to note that while these materials are non-toxic, they can release gases into the environment, but this problem is easily remedied through good ventilation or sealing applications in well-sealed enclosures.

These are just some of the seal materials that are often used; however, there are many more, so make sure to look around and find the right one for your needs.

Guest Contributor: Ruby Clarke