PORON Cushioning Blog Blog

PORON Cushioning Blog

The Science of Impact Protection – Materials have changed since the days of knights and steal armour.

Posted by Dave Sherman on Tuesday, February 22nd, 2011 | 2 Comments »

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.

Dave Sherman

Dave Sherman

Technical Design Solutions Manager at XRD® Impact Institute
Dave Sherman is the Innovation Leader at the XRD® Impact Institute - the research, design and testing facility of XRD® Impact Protection Technology. His experience involves a wide variety of foams including polyethlyene, polypropylene, EVA, rubber, polyurethane, silicone, and melamine. He has a Chemical Engineering degree from MIT and an MBA from RPI, as well as over 30 years of experience in the business of developing material solutions to meet demanding customer needs.

2 Comments

  • Troy Gordon says:

    Sir or Ma’am,
    I am a grad school student at the University fo Rhode Island and am looking at various protective products for our capstone project and was hoping. Can you tell me the melting point for Poron after it has cured into its solid (albeit squishy) foam state? Are there any chemicals it does not mix well with, like rubber cement adhesives or anything like that? Thank you for your time and help.

    Troy Gordon

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