This post written by David Sherman originally appeared on Rogers PORON Cushioning Blog.

You’ve probably heard quite a bit about concussions in the news lately.  In recognition of Brain Injury Awareness month, which takes place in March, the Brain Injury Association of America (BIAA) is launching a nation-wide campaign to ensure coaches of school athletic teams and extracurricular athletic activities are trained to recognize the signs and symptoms of concussions.

All of us at Rogers are excited to see that proper attention is finally being brought to the causes and effects of brain and impact injuries.  Extreme impact protection is the very reason we developed our PORON XRD technology, which is not only used in helmets, but also in compression garments, elbow and knee pads, and protective footwear.

As we travel around to trade shows all over the world, we are consistently asked how PORON XRD Material works.  How can such soft, flexible and breathable foam protect against something like a baseball flying at 100mh?  It all has to do with a short lesson in physics 101 and strain rate dependant materials.

Strain rate dependent materials are used in a variety of protective applications mentioned above.  They are useful in these applications because of their unique ability to adapt to the applied impact.  At low strain rates the material feels soft and contours to the body.  While at high strain rates the material instantaneously stiffens to absorb the impact and then returns to its original ‘resting’ state.

For those who want more technical information….

PORON XRD Material gets its softness when at rest or simply being worn, by being above the glass transition temperature (Tg) of the urethane molecules.  (Glass transition temperatures are similar to a melting point – for those who are not the foam geeks that we are.)

When stressed at a high rate or impacted quickly, the glass transition temperature of the material goes up to the point where the urethane momentarily “freezes.”  (Think of water freezing into ice.)  Many materials have glass transition temperatures, which is why strain rates are always specified in material testing.

When impacted, it is the firming of the material that allows PORON XRD Material to instantly form a comfortable, protective shell around the wearer.  Unlike many other materials which often maintain their “frozen” state, PORON XRD Protection immediately returns to its soft, flexible and contouring state.

For a more visual example, think of diving into water at a low height versus a higher height.  At low heights, jumping into water feels very soft and helps cushion the dive.  But at high heights (i.e. jumping from a bridge) the water feels like frozen ice.  This is due to the speed at which the person is entering the water.

Another example is to envision removing a Band-Aid™.   If you remove a Band-Aid ™ slowly, the

adhesive sticks to the surface, but if you remove it quickly, the adhesive freezes and sticks less.

PORON XRD Material was engineered to react very quickly in various impact situations.  For example, PORON XRD Technology is effective at absorbing not only smaller, repeated impacts (such as nudging players during a basketball game) but it is also effective at absorbing larger impacts (such as in a ballistic vest applications).  Rogers’ ability to manipulate the PORON XRD chemistry makes this unique material soft and flexible at rest or when it’s wrapped around your body, but instantly absorbs energy upon impact.

If you would like more information on all the various testing methods that we have conducted on PORON XRD Materials, we have plenty to share!  Just give us a comment below.

Please come back and visit us!  We will be posting some interesting news over the next several weeks in collaboration with our PORON XRD partners in recognition of Brain Injury Awareness Month.   As always, we would love to hear your questions and comments/views you may have on our products as well as how brain injuries/concussions are treated among team sports.

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2 Responses to The Science of Impact Protection – Materials have changed since the days of knights and steel armor

  1. We make protective headgear for soccer players. I am working with Rogers Foam Corp in Mt. Sterling KY and they sent me some of your samples. We currenty use 10mm, 3#, closed cell PE. I want to improve the performance of the product by changing over to xrd but I need help in understanding how your material might correlate with what I am currently using. I also have these questions: can it be laminated to other foam and fabric? can it be thermoformed? What thicknesses does the perforated material come in?

    Thanks, Bill I phone call would be nice 858 777 5176

    • Grant Juliann says:

      Thanks for the comment, Bill.

      It sounds like moving to PORON XRD makes sense based on what you have described. PORON XRD has all the beneficial characteristics of our other PORON Materials – dependable – long lasting comfort, breathable, flexible and have Microban antimicrobial protection. But PORON XRD Materials are specifically designed for impact protection when you need it most (like sporting equipment).

      We have a wide range of PORON XRD material combinations (and thicknesses) in order for customers to choose the level of protection that best suits their application and impact protection needs. We will have a sales engineer get
      in contact with you as soon as possible to further understand the specifics of your application. It’s hard to say exactly what you need at the moment, we’ll need more information.

      A little about PORON XRD:

      We have completed a wide range of impact testing for our materials (from baseball pitches to motorcycle back protection). PORON XRD Materials are considered a strain rate dependent material because of their ability to adapt to the applied impact. At low strain rates (or slowly pushing your finger into the foam) PORON XRD Foams feel soft and contours to the body. While at high strain rates (or quickly impacted) the foam instantly stiffens to form a protective shell around the body and then returns to its original
      ‘resting’ state. We do this because you wouldn’t need the same level of impact protection in your running shoe as you would a helmet.

      Feel free to visit: for PORON XRD Materials testing, adhesive guidelines and general product information.

      We will be in touch soon, Bill. Thanks again.

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