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.
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.
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.
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.
Density: 104 kg/m³ (lowest possible)
Thickness: 0.53mm, 0.75mm, and 1.00mm thick
Compressive Force Deflection Rating: 2.00 at 25% kPa
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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
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CONS
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
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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
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CONS
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
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CONS
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
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CONS
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.
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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
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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
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CONS
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
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CONS
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
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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