Types of Poron Foam and the Pros and Cons of Each

If you’ve ever had to source polyurethane foam, you’ll want to tear out your hair after hours hopping from one material page to the next. This time, take a moment to ask, What are my material requirements, and how can I compare PORON foams most effectively?

Polyurethanes are the largest class of polymers worldwide, and even their subcategories like PORON brand foam have many design variations. 

Strouse has helped prototype hundreds of parts using different variations of foam tape, meaning we know how to find the right variation to match our customer’s needs. 

As we examine these types of PORON foam, you’ll learn their purpose and what factors you should consider before making any final product decisions. 

What is Rogers Poron Foam?

PORON foam is a microcellular urethane with high compression set resistance and high energy absorption. Its open-cell design allows for greater resiliency and longevity, even after multiple impacts. 

The Rogers Corporation, the creator of PORON, has patented thirty-five PORON Industrial Polyurethanes. Each of their products utilizes PORON urethane foam's distinct properties to different ends. These open-cell polyurethane materials have solved many notable engineering challenges, including filling gaps in the Hubble space telescope.

PORON foam is meant to keep its shape, cushioning, and contouring precisely in response to pressure. These viscoelastic properties are derived from the foam’s microcellular design. Once the pressure is released, the cushioning foam expands to its full size or until it meets a new obstacle—a method of creating physical memory.

Open-Cell vs. Closed-Cell Foam

PORON foam's defining trait is its open-cell design. Before its invention, the most popular type of memory foam used a closed-cell design. 

Closed-cell polyurethane foams are filled with tiny, closed air bubbles or pockets that allow them to use air to cushion.  Over time, repeated compression causes air to leak out of the closed cells. Because the cells shut it out, air cannot return to the foam. This process of exhalation deflates the foam. 

In contrast, open-cell designs are more akin to microcellular springs. Compression lets the polyurethane springs condense, and air moves freely from the space. Meanwhile, the remaining air can support the pressure point within the micro-coils. After the pressure eases, air can easily flow back into the open cells and -re-inflate the foam. The foam expands, and both air and polymer support the pressure point.

Because open-cell design prevents deflation over time, PORON foam is frequently used in products designed to resist frequent, repeated impact. Running shoes and prosthetic limb interiors are good candidates for PORON foam and other open-cell polyurethane cushions.

Each PORON foam variety uses the same open-cell design to different ends. Some PORON foam products are more thermal resistant and thus make high-quality battery insulators. Others are lightweight and well-suited for absorbing sound waves. Therefore, the type of PORON you choose is very situation-dependent.

Types of PORON Foam and Their Advantages

When working with long-term tape for your projects, you'll want to ensure you choose the correct adhesive for the job. Let’s review eleven different types of PORON foam so you can see which might work for your project.

1. PORON 4701-15-06 (SOFT SEAL)

Density: 104 kg/m³ (lowest possible)

• Seal lightweight products or small gaps without throwing off the item’s weight

Thickness: 0.53mm, 0.75mm, and 1.00mm thick

Compressive Force Deflection Rating: 2.00 at 25% kPa

PROS

• • It makes an excellent dust seal to block out small particle contaminants or as a cushion to protect small, delicate materials. 
  • It is relatively soft and holds its shape well

CONS

• • It is not recommended for shock absorption in vehicles because it won’t withstand high compression forces. 
    
    

2. PORON POLYURETHANE 4701-30 SERIES

This series encompasses both PORON 4701-30-20 and PORON 4701-30-25. The impact foam PORON XRD is part of the 4701-30 series and lightweight enough to fit into apparel. 

Density: 240 kg/m³

Thickness: 4.78mm and 12.70mm thickness varieties

PROS

• • Highly durable, flexible, and compression set resistant
  • Absorbs sound waves and shock waves well
  • Its softness makes this PORON series useful in delicate applications, like cushioning batteries or electronic components. 

CONS

• • It isn’t well-suited for environments with frequent temperature fluctuations
  • It is not a very dense PORON foam, so it can’t be used in the heaviest-duty applications
    • It is not suited for dampening industrial noise but is an effective tool for dampening automotive noise.

3. PORON® AQUAPRO™ 4701-37 SERIES

The PORON® AquaPro™ Series includes 4701-37 Thin, 4701-37-14, 4701-37TS9-19, and 4701-37TS9-25.

This series was designed to protect components from potential water damage and to seal contained water. The PORON AquaPro Series uses PORON's expansive, space-filling properties and bolsters them with water-resistant capabilities. 

Density: 304 kg/m³ to 400 kg/m³

PROS

• • Long-lasting 
    • Retains its set compression over long durations and doesn't corrode
  • Environmentally safe, with zero risks of any plastic migration
  • It doesn’t require a significant compression force to achieve a tight seal
  • Flame-retardant
  • Resists many automotive chemicals

CONS

• • Only intermittently stable in high-heat (120ºC) conditions
    • For high-heat applications, you may want to select a different PORON foam
  • Not the most shock-absorbent foam
    • Not recommended for maximum-impact scenarios. 
      
      

4. PORON 4701-40 POLYURETHANE

The PORON 4701-40 Polyurethane series encompasses 4701-40-15, 4701-40-20, and 4701-40-30.

This polyurethane foam series is composed of the second softest PORON foams. Some of its softness is traded for higher tensile strength than the 4701-30 series.

Density: 240 kg/m³ to 480 kg/m³

Thickness: from 0.70mm to 12.7mm

PROS

• • Handles extreme temperature fluctuations without warping
    • This polyurethane can function in temperatures as low as -40ºC and as high as 121ºC.
  • Its density and tensile strength make this foam well-suited for shock absorption
    • The open-cell polymer quickly absorbs and diffuses mechanical shocks, drops, and vibrations.

CONS

• • It is not notably waterproof or anti-bacterial, so choosing a different PORON product for sealing is best
    
    

5. PORON AQUAPRO™ CLOSED-CELL VACUUM SEAL 4701-41

This PORON foam product line differs from everything else on this page because it is the only closed-cell foam. They're intended to be vacuum-compressed and create a solid, airtight seal upon compression. 

This series includes PORON AquaPro™ 4701-41-15, 4701-41-20, and 4701-41-30. 

Temperature: thermally stable at consistent temperatures as low as 40°C and high as 90°C

PROS

• • Resists most chemicals
  • Safe for the environment
  • Durable for long-term performance
  • Can meet or surpass low closure-force requirements mandated in specific aviation applications

CONS

• • Will not revert to an expanded state after it has been vacuum-sealed (due to its closed-cell structure)
  • It cannot be reused for other applications.
    
    

6.  PORON 4701-50 POLYURETHANE

The PORON 4701-50 line of polyurethane foams is firm. These foams are made for high-impact, high-energy gaskets. They have a high compression set deflection rating and are denser than other PORON foams. 

Density: 240 kg/m³ to 480 kg/m³

Temperature: withstand fluctuating temperatures from -40°C to 121°C

PROS

• • Firm and somewhat dense polyurethane 
    • It has less "give" than softer foams
    • Resists moderate impacts and effectively cushions or absorbs intense impacts
  • Ample durability, longevity, and energy efficiency.

CONS

• • Isn’t soft or resistant to all chemical fluids
    • Exposure to some chemical fluids may cause this polyurethane to swell. 
      
      

7.  PORON 4701-60 POLYURETHANE

The PORON 4701-60 is a very firm series of PORON foam. The series encompasses 4701-60-15, 4701-60-20, and 4701-60-25. It can deflect waves and vibrations for an extended period without losing shape or stiffness. 

This is one of the most durable PORON products. It resists tearing, corrosion, mildew, and bacteria.

PROS

• • Firmness and resilience allow it to create seals or gaskets in hot machinery
  • Absorbs frequent, high-intensity shock waves or sound waves

CONS

• • Not soft = unsuitable for cushioning a human body directly or any delicate electronic components
  • It is not recommended to use 4170-60 to fill small gaps
    • Its firmness might prevent it from expanding precisely into the necessary shape in a small space.
      
      

8. PORON V-0 FOAM

PORON V-0 foam is both HBF and UL94-V-0 certified for passenger safety.

Density: 400 kg/m³

Temperature: functions in temperatures as low as -20°C and as high as 90°C

PROS

• • The safest PORON foam for humans
  • Surpasses high standards for flame resistance and durability
  • Firm & easy to die cut with precision
    • It will retain its shape long-term after being cut. 

CONS

• • It isn’t very soft or flexible or notably resistant to mildew or bacteria
    • Not well-suited to contexts where it will be continuously exposed to dampness. 
      
      

9. PORON SHOCK SEAL™ FAMILY

The PORON Shock Seal™ Family of foams includes 4790-79-09, 4790-79-12, 4790-79-15, and 4790-79-20. Rogers Corporation sometimes categorizes these foams as "display back pad foam." 

It is also flexible. The combination of firmness and flexibility allows it to absorb impacts precisely, even in a small space. 

Density: 240 kg/m³ to 480 kg/m³

PROS

• • Easy to shape and contour. 
  • Due to their firmness, these foams can absorb huge shock sound waves and dampen high-decibel sound
    • This brings dangerously loud industrial noise down into a safe range for human hearing.
  • This family of foams effectively mitigates frequent, intense, or unpredictable shocks.

CONS

• • It is too firm to be any good for gap-filling
  • Not waterproof or flame retardant
    • It is not recommended in cars, aircraft, or electric vehicles.
      
      

10. PORON 4790-92 POLYURETHANE FOAM

The PORON 4790-92 series is made of extra-soft foam. It rebounds slowly after any pressure is released. 

Density: 144 kg/m³ to 480 kg/m³

Thickness: 0.53mm to 12.7mm thick

Temperature: functions in temperatures as low as -20°C and in environments where the maximum temperature reaches 121°C

PROS

• • The extra soft nature of this foam extends its life
    • It keeps it lightweight while still effectively absorbing low-energy impacts.
  • It manages continual low-impact vibrations
  • It can be exposed to damp environments, as it is bacterial and mildew-resistant

CONS

• • The impact limit is designed to absorb low-energy impacts only
    • Not suitable for large-scale noise or vibration management.
  • It tends to swell when it absorbs water
    • It cannot be submerged
  • Not particularly resistant to automotive fluids. 
    
    

11. PORON EVEXTEND® 4701-43

The PORON EVExtend® is a material intended to cushion the batteries of electric vehicles. Its most unique property is its flatter compression force deflection (CFD) curve. 

This flatter curve works with the battery's natural cycle of contraction and expansion. To absorb and distribute force effectively when the degree of compression is constantly changing, the Rogers Corporation developed foam with a firm-to-soft gradient in each individual piece.

These materials are firmer at the front to maximize their impact-absorbing effects in the direction most impacts come from. The softer back slowly expands to cushion the battery. Due to this gradient, the PORON EVExtend® has no consistent density throughout. 

Temperature: functions in temperatures that range from -20°C to 90°C

PROS

• • Durable polymer with a long life.
  • Effective shock absorption where low-density materials are mandatory
  • Halogen-free and UL-certified as flame-resistant

CONS

• • Not waterproof
  • It isn’t particularly versatile and has a highly specific utility
  • Not typically the best choice for any project beyond interfacing with an electric vehicle battery
    
    

Finding the Right PORON Foam

Each type of PORON polyurethane has advantages, so which PORON foam do you need? Foam suppliers will recommend a range of products based on your project; however, if you’re seeking a custom part component, you may want to reach out to a converter first. 

Die cut PORON foam can be customized to your project's exact needs while maintaining the efficiency of mass production. Depending on your intended use case, a material converter can help you find an easily manufacturable solution. 

If you’re interested in trying out different types of PORON foam for your design, contact Strouse for custom samples. If you’re curious about other types of foam, you can learn more about foam tape and other adhesive materials in our Learning Center. 

Originally published: August 8, 2022