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Brentwood Plastics blog

Plastic Films Substituion

Posted by Joel Longstreth on Fri, Oct 04, 2019 @ 06:13 PM

Everybody wants replacements for politically incorrect plastic films to be exactly like the original.  No property trade-offs.  No exaggeration. 

substitutebrocaulifsubkidssubmilk

Would these same people expect the same results from direct substitution of stevia, xylitol or saccharin ?

There are many drivers.  Back in the 1990's when PVC started to fall out of favor, we got calls for PVC replacement.   The major complaint about our metallocene which mimicked the "hand" of vinyl was that it did not seal in the heirloom RF sealers.  The expectation was that a non-polar molecule would behave just like a polar molecule.  Reluctantly, new sealing techniques were developed as a work around. 

tantrum

Skip ahead to this past summer.  We got literally dozens of calls for our equivalent to PVC cling wrap for packaging corn because WalMart does not want PVC in their stores.  Even if they found a polyethylene that was clear enough and ran in the usual machine, the shelf life would not be the same due to difference in permeability. 

freshcorn

PEVA ( polyethylene with ethylene vinyl acetate ) has emerged as the film of choice for shower curtains because it is not PVC and is sealable by RF with minor modifications.  

We wasted a lot of resources developing a substitute for PVC in commercial wallcoverings.  The greenbuild culture despises PVC but they are stuck with it.  Only PVC passes E 84 because it is naturally self-extinguishing.

The interest in percieved sustainable films has hit a tipping point as products are being designed for more of a "circular" than "linear" economy.   Designers are finding there are many frustrating hurdles to overcome.

hurdles

 

Just when you think you've seen it all department - today somebody inquired about a substitute for a coextrusion of LDPE / Nylon / LDPE.  They wanted a certifiably compostable film just as tough as the coex structure with the sealability to nonwoven.  At first I thought it was a prank.

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Topics: PVC free plastic, PVC free, PEVA film, PEVA, Non - PVC, PVC substitute, sustainable packaging,, green plastic

EVA and PEVA - be specific

Posted by Joel Longstreth on Tue, Nov 08, 2011 @ 12:25 PM

EVA and PEVA are both acronyms for Ethylene Vinyl Acetate.  Somehow the P for polyethylene was added to create the acronym "PEVA."

To make EVA copolymer, Vinyl Acetate Monomer or "VAM" is copolymerized, or conjoined with Ethylene monomer to make Ethylene Vinyl Acetate. 

EVA copolymer is made in varying percentages from 2% EVA, 4% EVA, 6% EVA, 8 % EVA up to about 28 % EVA for blown film.  If you order simply "EVA" it is too broad and not specific enough.
The percentage of EVA is critical because the greater the EVA component, the lower the melting point.  This affects the EVA film performance properties.  If you are RF welding, the more EVA is needed for response to RF frequencies.  For low melt / total batch inclusion, the amount of EVA must be known to match with the desired melting point.  EVA is popular for solar photovoltaic pv cell encapsulation, yet EVA film suppliers do not specify the percent of EVA in the film for solar panel manufacturers.

When ordering EVA film, be sure to specify the amount of EVA for consistent performance.

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Topics: EVA sheet solar, EVA film, solar panel manufacturers, PEVA film, PEVA, EVA film supplier

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