This post (originally by Dave Sherman) appeared on the PORON Cushioning Blog. Updated 08/21/2018

A Foam is a Foam is a Foam, Right?

In a word (or three), not so much. Our customers are often surprised to learn that all PORON® Comfort materials are open cell polyurethane foams, especially when what they’re used to seeing are closed cell EVA foams or closed cell polyurethane foams.

Open cell foam has many benefits and properties not present in closed cell foams. One of the biggest is that it offers the best resistance to compression set (C-Set) or, for the non-foam aficionados out there, resistance to break down after multiple uses. Essentially, this means that the foam is very durable and won’t break down or lose its cushioning properties after multiple uses. In the footwear world that equates to a consistent fit, form, and functional level, and maintains the look and feel of the shoe as it was designed.

Closed Cell Foams vs. Open Cell Foams

Here’s something else to consider…

Closed Cell Foam:

Closed cell foams, or EVA foams, are comprised of complete bubbles of air. The bubbles of air are trapped in the foam with cell walls all around that prevent air from escaping. Bunched together like soap bubbles in a bubble bath, the air pockets are crucial to the function of the foam. When the foam is compressed, so is the air inside the bubbles, which allows the foam to spring back when pressure is removed. For this reason, they are often used in shoe insoles and sports padding where resistance and protection are key.

Evidence of this property can be demonstrated with a tennis ball. Tennis balls are known to be bouncy due to the air trapped inside the ball. But once a tennis ball has been used repeatedly the air begins to leak out, causing the ball to lose its springy resistance.

tennis ball - closed cell foam

Applying this analogy to closed cell foams, this is the point at which the foam begins to go flat or “take a set” (remember that whole C-Set thing?). That’s why insoles or padding made solely from closed cell foam become less comfortable over time or are less protective on the next hit.

Open Cell Foam:

Open cell foams have their plusses and minuses as well. PORON Comfort materials are comprised of open cells connected by portals which allow air to flow between them.

This means these materials are not dependent upon air bubbles for their properties, but instead on the properties of the materials in their cell walls. Because of this, they react to pressure in a manner similar to that of a spring, returning to an original position after each compression without fail due to air moving freely through the cells. An open cell structure also allows for moisture vapor transmission, helping with breathability and maintaining the environment of the shoe.

spring - close cell foam

Available in an array of proprietary formulations, PORON Comfort open cell materials are engineered to provide specific functionality, providing the right level of support and breathability to the end user throughout the day and over the life of the shoe.

So Which One is Right for Your Application?

There are advantages and disadvantages to each type of foam that should be considered when deciding which one to use. Closed cell foams can be very light, as their cell walls can be very thin, but are usually stiff because of the incompressibility of the air inside them. They can also be better than open cell materials at resisting liquid penetration.

Open cell foams, in addition to being resistant to taking a set, are softer and easier to compress. Their cells also allow for breathability and a better Compression Force Deflective (CFD) or, in other words, a measure of their firmness or load-bearing capacity.

Occasionally the right foam solution is actually a combination of closed cell and open cell materials. Capitalizing on the best of both worlds, some designs layer a closed cell foam and open cell foam, allowing the more flexible open cell layer (such as PORON Comfort) to conform to the shape set into the closed cell material (an EVA for example).

Refer to the table below for a summary of the advantages of each type of foam:

Foam Properties Open Cell Closed Cell Property Measurement
Compression Force Deflective (CFD) Softness/Conformability
Compression Set Resistance Life of Properties
Anti-Microbial  ✓* Integral Coating
Breathability MVTR-Yes/No
Water Absorption % Uptake After Some Time
Washability Cycles at Setting

*Optional additional protection available

Be mindful of these differences as they relate to your application and design.  If your application requires lighter weight and washability, opt for a closed cell foam. However, if longevity and reliability are critical to your application, choose PORON Comfort materials as your solution.


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A huge thank you and best wishes to Fred Seidel, Customer Service Manager, on his retirement from Rogers. Known as Mr. PORON, Fred has a deep and extensive knowledge of all of Rogers’ elastomeric products, including the PORON® family of polyurethane materials. From its beginnings as a sintered vinyl used as an insole wrap in the shoe industry, to today’s wide range of formulations, PORON materials deliver durable, long-term performance in gasketing, sealing, and cushioning applications. Fred’s professional expertise will be greatly missed. Again, our best wishes go with you Fred – enjoy your retirement!


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New Developments in Battery Technology

On November 2, 2015, in Technology Update, by sharilee

Tech companies and car manufacturers are making big investments in battery technology. And for good reason. Sales of electric vehicles (EVs), including battery-electric vehicles (BEVs) and plug-in hybrid vehicles (PEVs) are soaring, especially in the EU where gasoline prices are 2-4x higher than in the U.S. IncHEVreased use of mobile devices is also driving the need for battery innovations, even as chips and operating systems are designed to be more efficient and save power. The latest IDC Worldwide Quarterly Mobile Phone Tracker shows 6.8% growth in smartphone units shipped in Q3 2015 vs Q3 2014 to over 355 million units. Add to that, growth in wearables, laptops, tablets, and smart homes.

But battery technology has been slow to change over the years. Li-Ion has dominated to date because a lithium anode has a high energy density and is lightweight. In an interesting article, “Why We Don’t Have Battery Breakthroughs” in MIT Technology Review, Kevin Bullis writes:

One difficult thing about developing better batteries is that the technology is still poorly understood. Changing one part of a battery—say, by introducing a new electrode—can produce unforeseen problems, some of which can’t be detected without years of testing.

In startup Envia, they had licensed a promising material developed by researchers at Argonne National Laboratory. Subsequently, a major problem was discovered. The problem—which one battery company executive called a “doom factor”—was that over time, the voltage at which the battery operated changed in ways that made it unusable. Argonne researchers investigated the problem and found no ready answer. They didn’t understand the basic chemistry and physics of the material well enough to grasp precisely what was going wrong, let alone fix it.

The single most important factor in achieving a mass-market BEV is cost. “Estimates are that the cost of battery packs needs to fall to below US$150 per kWh for BEVs to become cost-competitive with internal combustion vehicles,” said Bjorn Nykvist and Mans Nilsson in their Nature Climate Change paper, “Rapidly falling costs of battery packs for electric vehicles.” For Li-Ion battery packs, costs have decreased over the last 8 years, from above US$1,000 per kWh to around US$300 per kWh.

Innovations in Li-Ion Battery Design

New developments show much promise. According to Brookings Institution’s TechTank blog:

Lithium heats up and expands during charging, causing leaked lithium ions to build up on a battery’s surface. These growths short-circuit the battery and decrease its overall life. Researchers at Stanford recently made headway on these problems by forming a protective nanosphere layer on the lithium anode that moves with the lithium as it expands and contracts.

Screen Shot 2015-11-02 at 10.00.19 AM

Figure 1. Movement of lithium ions and electrons in a Li-Ion battery during charging and use.

Israeli startup StoreDot has developed a new type of Li-Ion battery that it says can be fully charged in a few minutes. In a standard Li-Ion battery, the internal resistance blocks the flow of the current and makes it more difficult to deliver spikes of power. StoreDot is using bio-organic peptide “nanodots” to make very thin battery electrodes with supercapacitor-like rapid charging and a Li-Ion-like slow discharging.

Beyond Lithium Ion

Researchers at BASF recently doubled the amount of energy that can be stored in an older type of battery, nickel-metal hydride, now used in HEVs. This makes them comparable to Li-Ion batteries in terms of storage, but with the advantage of increased safety. They don’t use flammable liquids, so their cooling systems and electronic controls are simpler. The scientists changed the microstructure of the batteries to make them more durable and lighter. They can store 140 watt-hours per kilogram. Li-Ion can store up to 230 watt-hours per kilogram, but the added weight counters that advantage.

Scientists at UCLA’s California NanoSystems Institute have developed a hybrid device that goes beyond simple changes in battery cell chemistry. According to Green Car Reports:

The experimental device combines the energy density of a lead-acid battery with the quick charge and discharge rates of a supercapacitor. It’s six times as energy-dense as the average commercial supercapacitor. That combination of qualities has great potential impact for electric cars. It would theoretically offer more compact energy storage and faster charging without sacrificing range.

Researchers claim the version being tested can hold twice as much charge as a typical thin-film lithium battery–but on a surface one-fifth the thickness of a piece of paper. This performance was reportedly achieved by maximizing the contact area between the electrolyte and the two electrodes. Those electrodes are made from manganese dioxide, but feature a three-dimensional laser-scribed graphene (LSG) structure.

Second Life Battery Applications

EV batteries lose their ability to propel a vehicle over time.There is a growing market for EV batteries in after-life commercial applications, such as power generation on the grid. GM, for instance, is using the Volt battery system to supplement renewable power gen at one of its facilities, making the facility a net zero building. Nissan and Green Charge have developed ex-EV battery systems that companies can use to manage their utility demand charges, substituting battery power for electricity from the grid during peak pricing.

Eventually, carmakers will incorporate EV batteries while they’re still installed in cars, using vehicle-to-grid (V2G) systems. Such an approach promises better regulation of frequencies on the grid to smooth the power loads and lower usage during peak demand periods. The U.S. Department of Defense has invested $20 million in the DoD Plug-In Electric Vehicle Program, which has so far installed 500 V2G-enabled vehicles at bases in the states. This program has shown that frequency regulation alone can reduce the monthly lease price of a plug-in electric sedan by 72%.


Regardless of the application, batteries need to be packaged to absorb internal impact energy. PORON® polyurethane and BISCO® silicone foams withstand collapse that can happen due to the stresses of compression and temperature in battery packs over time. This Compression Set Resistance (C-set resistance) can help extend the life of the battery by continuing to seal and absorb shock. These unique foams from Rogers Corporation also have a unique ability to act as a spring by retaining a very consistent level of force across a range of compressions. This allows the designer more flexibility and reliability in packaging of the battery pack due to the ability to predict the cushioning material’s behavior across varied dimensional tolerances.

Tangible improvements in battery technology are surfacing. This will have a significant impact on our use of EVs and mobile devices, and, when combined with developments in renewable energy, will drive interesting global changes in economic and political norms.

The bond matters most…

PORON_foam_tapeOEMs that design and manufacture smartphones and tablets are always looking for better ways to protect devices from damage by the environment and by sudden impact. Rogers recently introduced PORON® Foam Tape, a solution for both display bonding and impact protection. The product combines bond strength, compression set resistance, and dimensional stability to prevent window floating. In addition, the tape delivers optimized water-sealing performance, passing the Rogers IPX7 simulation test under zero compression.

And now PORON Foam Tape is in the news around the world:

InformationWeek — Introducing PORON® Foam Tape Window Adhesive

Konsreuktions Praxis —  Scheibenklebeband mit hoher Stabilität

ThomasNet News — Urethane Foam Tape prevents window delamination

TMCnet World NewsIntroducing PORON® Foam Tape Window Adhesive

Rubber NewsRogers unveils foam tape for smart phones, tablets

Mobility Tech ZoneIntroducing PORON® Foam Tape Window Adhesive

Blog ol — Rogers puts out PORON foam gummed tape and looks at the binding material of window glass

EIN World NewsIntroducing PORON® Foam Tape Window Adhesive

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Minimalist footwear has caught the eyes of The Doctors!  The award-winning television series featured ZEMgear with PORON® Performance Cushioning in a fitness segment that aired on May 9th on NBC.2Cinch-Sky-Black-Lg

Dr. Travis Stork discussed the features of barefoot technology footwear, in particular the benefits of split toe styles, which allow for maximum foot flexibility and agility.

As we reported in an earlier blog post, ZEMgear creates Performance Protection for Bare Feet™, delivering minimal footwear with maximum protection for men, women, and children.  ZEM, (Zone of Endless Motion), allows feet to do what they were designed to do best in their natural, barefoot state. PORON Technology, used in ZEMgear insoles, provides unique cushioning and impact-mitigation benefits to consumers.

Watch the fitness segment here…

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