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Brentwood Plastics blog

Metallocene VS EVA

Posted by sam Longstreth on Tue, Jun 21, 2011 @ 11:33 AM

In it's day, ethylene vinyl acetate ( EVA / PEVA ) was a game changer.  It enhances physical properties and sealability.   When added to homopolymer polyethylene in small amounts (1 to 3%) it improves the clarity.  When added in higher percentages (4 to 6%) it further enhances sealabilty and improves cold stress crack resistance.  At the 4 to 6% loading the optics of the film decrease due to the high amounts of antiblock needed to prevent the film from sticking to itself.  

The drawbacks to EVA are tackiness and odor.  It has a pungent apple bouquet which makes it unacceptable for dairy products.

Metallocenes have better optics, better physicals, a lower heat seal initiation temperature, better cold temperature stress crack resitance, less taste transfer, less expensive and offers a better opportunity for downgauging than EVA's.  

Legacy specs often call out EVA which is of course often difficult to alter.  A blend of the right metallocenes can easily mimic an EVA.. 

Back in the 1990's when metallocene burst on the scene, many predicted the demise of EVA. Skip ahead to present day.  Turns out each has it's place.  EVA is a popular substitute for PVC and for adhesive layer of solar panels.  It is still used for total batch inclusion. 

We offer both EVA and metallocene.

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Topics: metallocene, EVA, PEVA

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