Sponge Rubber vs Foam Sheet (PE & EVA) - What is the Difference?

In the world of sealants, padding, stripping, and squishy sheeting, you have two main material options: sponge rubber and PE or EVA foam sheet. 

These materials are extremely functional, and they can appear quite similar. However, when you take a closer look at their composition and characteristics, you will realise that they are very different. For technical buyers, these differences make all the difference. 

Let’s take a look at what the main differences are and why they matter so much.

Difference in Production

The difference starts at production. Here is a quick look at how foam and sponge rubber production methods vary;

01. Foam Sheet Production (PE & EVA) 

This type of foam is created by adding a “blowing agent”  into melted polymers. This fills the polymer with gas during the “foaming process” that then creates cells much like tiny balloons when it is subjected to heat & pressure .This foaming is usually done in two steps, that being a primary foaming after being in a high pressure press then a secondary foaming  in an open  press.  PE & EVA foam sheet is closed cell so non porous creating an air, water & moisture seal. It also is available in various densities, the higher densities being firmer. 

02. Sponge Rubber Production

A blowing agent is mixed with the rubber polymer during the mixing stage. The mixture is then subject to heat & pressure before being  allowed to “expand” instantaneously when the press opens. The sponge structure is created as gas bubbles occur and swell throughout the mixture of ingredients as it expands. This creates the “spongy” sheets that are strong so have excellent recovery (compression/deflection) characteristics. 

Characteristic Differences

These materials are very different in the way they look, feel, and can be used. Here are some key performance differences;

Water and Gas Resistance - Closed-cell sponge rubber and PE & EVA foam sheet won’t absorb any moisture, dirt, or gases, making them an ideal sealant but gas resistance depends on the base polymer of the material

Density and Elasticity - Sponge rubber is more elastic and has better recovery characteristics but is more expensive & in most cases, more dense. 

Temperature Resistance - Sponge rubber can be made to handle extreme temperatures that range from -40 degrees C to 120 degrees C. Foamsheet (PE & EVA) , on the other hand, will only hold up in moderate conditions of -25 degrees C to 80 degrees C.

Application Differences

Because these materials are so different and perform so differently, you cannot use the same product for all applications. Here are some of the best uses for each type;

PE & EVA Foam Uses - These are best for comfort cushioning or impact dampening. It is often used for sports or safety padding, flotation devices, or as a light cushion.

Sponge Rubber Uses - This type of product is mostly used for industrial or commercial applications. It can be used in the automotive industry as a gasket, seal, or soundproofing, or can be useful in properties as weatherstripping. 

Find the right closed cell sheeting

If you want the best functionality and the best performance, then it is important to start with the right material. At Gardiner Australia, we can guide you to the right material for every use. We welcome you to reach out to us if you want to find out more about our materials or products, or if you need help choosing the right product for your project.

Contact Gardiner Australia and find a product type that is just right.