Comparing Polyethylene Foam And Polyurethane Foam: Key Differences

What's the Difference Between Polyurethane and Polyethylene Foam?

Although their names sound alike, polyurethane and polyethylene foam are quite different in composition and performance. Both belong to the broader family of foam materials, but they serve distinct purposes. Understanding these differences is essential when selecting the right foam—whether you're designing a product component or choosing protective packaging.

These are the fundamental characteristics of two of the most widely used types of foam.

What is Polyurethane Foam?

Polyurethane foam is a soft, low-density material classified as open-cell foam. Its cell structure is not cross-linked, allowing air to pass through freely. This gives the foam a flexible, compressible feel when pressure is applied. Known for its excellent shock absorption and flame resistance (meeting UL 94 safety standards), polyurethane foam is also easy to cut and shape, making it highly versatile for a variety of applications.

Polyurethane foam is generally classified into two major types:

1.Ester-based polyurethane features a finer cell structure, giving it a firmer, more supportive feel and greater durability. While it provides superior shock absorption, it is highly vulnerable to moisture and water damage.

2.Ether-based polyurethane has a larger cell structure, allowing greater airflow and moisture resistance. It offers a softer, more flexible feel compared to ester-based polyurethane.

Polyurethane is commonly used in cushioning and many other applications.

What is Polyethylene Foam?

Polyethylene foam is a dense, closed-cell material known for its firmness and excellent resistance to hydrolysis—it won't degrade when exposed to water or moisture. This durability comes from its closed-cell structure, which prevents the passage of air and liquids.

Crosslinked and expanded molded polyethylene foams are ideal for thermal insulation and sound dampening. These foams can also be laminated to enhance protection against heat, gases, and other harsh elements.

Another variant, beaded polyethylene foam, is a hard yet low-density material that remains flexible and easy to fabricate. It's non-abrasive, odorless, and a highly effective insulator, making it especially useful in marine applications for both support and comfort.

Using Polyurethane and Polyethylene Foams Together

In some applications, both polyurethane and polyethylene foams are used together to maximize performance. A common example is in cushioning products, where a soft polyurethane foam core is layered beneath a firmer polyethylene foam top. This combination creates a sturdy surface with underlying comfort and shock absorption, making it ideal for seating, athletic mats, and similar uses.

Need help selecting the right polyurethane or polyethylene foam for your project? Our foam fabrication experts at TOPSUN are here to assist. Contact us today!