Choosing Polyurethane or Silicone Foam Rubbers for Gasket Construction

Dec 29, 2015 Gaskets | Materials

When designing custom gaskets, polyurethane and silicone foam rubber are popular options among customers. Some customers believe that they are one and the same. While they be similar in certain characteristics, these two materials are miles apart. If you are a design engineer or a technical buyer, you will need to understand the differences between these two materials, before you use or purchase them.

Understanding the Basics

The points below provides the common characteristics of these two materials.

Both silicone and polyurethane provide resistance to fire and UV rays.
As foam rubbers, they both offer cushioning as well as insulation.
They can be designed with an open or closed cell structure, depending on the application.

Differences between Foam and Sponge Rubber

The following points can help you understand the differences between the two materials.

Polyurethane Foam Rubber Gaskets: Polyurethane gaskets are generally designed as open-cell polyurethane foam. They comprise interconnected pockets that allow the passing of air, water, and chemicals when the material is not compressed. Due to this, the gaskets provide excellent cushioning. Polyurethane foam rubber gaskets can be used in medical, research, packaging, and electronic industries.

Silicone Foam Rubber Gaskets: Silicone foam gaskets can be designed in different firmness grades depending on the application’s compression requirements. They can be soft, medium, firm, or rigid. Silicone is known for its high flame resistance low compression set, and temperature stability. Silicone foam rubber provides benefits of chemical inertness and being non-toxic. Hence, they are always chosen for applications with emphasis on sanitation and sterilization. Due to this, they are generally designed as closed cell silicone foam. Their cells are filled with gas, which prevent the absorption or passing of air, water, and chemicals at low pressures.

As you can see, these two materials have certain similarities as well as differences in terms of characteristics and application. The use of silicone and polyurethane gaskets depends on the application requirements. Hence, it is important that you understand the application needs before you use a material. You can also take the help of a seals manufacturer to find the best option.