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Merryweather Foam Blog

Since 1948, we have been industry leaders in fabricating unique, foam components for customers in the medical, sound absorption, automotive, and unique packaging industries. At Merryweather Foam, we pride ourselves on our ability to combine experience, innovation, and excellent customer service. We have the knowledge, manpower & equipment to help you get the job done. Visit our website to see our fabrication portfolio as well as our capabilities.

Polyester Polyurethane Foam or Polyether? Know the Difference

There's much to consider when buying flexible polyurethane foam. Density, tensile strength and Indentation Load Deflection are all important, but before looking at those there's a more important property to consider: which type of foam will work best in the application? 

There are two types to choose between: polyester polyurethane foam, and polyether polyurethane foam. Put side-by-side they're virtually indistinguishable, yet the differences in their properties could have a big impact on how your foam-based product performs. This blog post explains the differences and addresses why one might work better than the other.

A Little Chemistry
A polyester is a compound made up from multiple esters, linked in various chains. An ester starts out as carboxylic acid, which consists of carbon, oxygen and hydrogen. Adding an "alcohol," which in the chemical sense means a hydrocarbon compound like ethyl, replaces the hydrogen atom with a carbon-hydrogen compound. The result is a longer chain where the carbon and oxygen form a strong bond.

Ethers are only slightly different. Still a hydrocarbon, the oxygen forms two bonds to hydrocarbon compounds. One of the consequences is that ethers tend to be hydrolytically stable, or put more simply, don't break down in the presence of water. This is one of the major differences between the two types of foam.

Properties of Polyether Foam
Foams made with ethers hold up well in wet conditions. They are generally soft and flexible, due in part to relatively large pores. They are also easier to make and so less expensive than polyester foam. That's one reason polyether outsells polyester.

Polyester Foam Properties
Pound for pound, polyester foam is stronger than polyether and more rigid and supportive. Resistant to attack by many corrosive gases, it accepts additives providing fire-retardant properties and can also be formulated with electrostatic discharge (ESD) characteristics. (This type of foam is typically recognizable by its pink color.) Polyester polyurethane foam pieces can be welded together and it can be flame laminated, (where heat produces slight melting on one surface, letting it bond to another material.)

Two disadvantages against polyester are that it is:

  • Hygroscopic, meaning it deteriorates in damp conditions.
  • More expensive to produce than polyether.

Which to Use:
In general, polyether polyurethane foam is the material to use when cushioning is important, and especially if it might get wet. (Fabric-covered seats on a boat are a good example.) However, if the foam will be stretched or pulled, (as might happen when upholstering furniture,) or will be used for support and protection, (like in a transit case,) then polyester foam is the better choice. If the application is protection of electronic components then ESD protection should be considered, making polyester the only choice.

Consider the Application
Choosing polyurethane foam involves more than just looking at density; it's important to select the right type of foam for the application. Polyether polyurethane foam is generally softer, less expensive, and doesn't degrade when wet. However, if ESD protection or support are important, choose polyester polyurethane foam. Need more help? Give us a call and we can help you compare materials for your application. 

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Choosing the Right Foam Product for Acoustical Insulation

Acoustical foam is a cost effective way to improve the quality of sound in a room. Contrary to what many believe, foam does not block sound, but absorbs it. Sound waves propagate through the air and reflect from surfaces to produce echoes. When sound waves enter the pores of the foam, the sound energy is converted to kinetic energy. It is transferred to the foam, causing it to vibrate. This prevents the sound waves from reverberating throughout the room. Acoustical foam is available for use on walls and ceilings. It is frequently used to control noise in auditoriums, recording studios and conference rooms and reduce vibrations in industrial settings.

Types of Foam
Melamine and polyurethane are the primary materials used to produce sound absorption foam. Polyurethane is tear resistant and may be found in a wide range of colors, textures and styles to allow limitless design possibilities. Polyurethane foams are available as either polyesthers or polyethers. Polyesthers are more robust, glossier and maintain their color longer than polyethers. Polyethers are less expensive. Polyurethane acoustical foams are Class B Fire Rated. The material is highly flammable and should not be used near high heat or open flames. Melamine is not quite as durable as polyurethane but has a Class A fire rating. It is often the choice of builders since it meets fire codes. Melamine is fire resistant and used in public areas such as hospitals, schools and cafeterias.

Foam Shapes
Acoustical foams are produced in a variety of shapes and sizes to enhance performance and increase specific sound absorption properties. Convoluted foams, such as the egg crate pattern, are designed to increase the surface area to provide greater absorption of sound waves. Wedge foam, with a one inch thickness, offers moderate sound control and is most effective for mid to high range frequencies. Increasing thickness to 2 to 4 inches increases the foam's ability to absorb a full range of frequencies. Though similar performance improvements are observed with increasing thickness, the increased surface area resulting from the unique geometry of pyramid foam offers a slight performance improvement over the wedge foam.

Acoustical foams are lightweight and easy to install. To be effective, all wall surfaces of the room must be insulated with foam. Applying it to only one wall allows the sound to reflect from the remaining uncovered walls. The type of foam needed to treat your room will depend on the size, shape, surface texture and frequency of sounds.

How can we Help?
Let us help you select the right flexible foam product for your next project. We would love to answer any questions you have about custom foam fabrication.

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