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Re: [GreenYes] /All PET "Can"
Another question worth asking:
what about the various (usually toxic) chemicals that migrate, even at room 
temperature, into the liquid contained by PET?

Muna

On 3 Jan 2003 at 14:04, Peter Anderson wrote:

> In light of Wayne's question (below), I should have added a salient
> comment to the information I posted from the Schotland press release
> concerning the all PET beverage can.
> 
> Monomer PET does have excellent barrier properties, which is why it
> was engineered 20 years ago to also have the molding economics it
> needed to prevail in the marketplace.
> 
> However, physics dictates that as a container's size decreases, the
> need for barrier performance increases. This is because the ratio of
> the exterior surface increases as a function of the interior volume
> with decreasing size.
> 
> PET works just fine keeping carbonation in 2-liter bottles, and
> indeed, down to 16 ounce bottles. However, it does not provide
> adequate shelf life to keep pop from going flat in 12 oz. containers.
> 
> We've all heard about the need to enhance PET's barrier performance in
> all size plastic bottles for beer due to beer's intense sensitivity to
> oxygen infiltration.  That led to a number of different barrier
> enhanced designs such as that used by Miller beer beginning in 1998.
> 
> Well, whether we're talking about a PET bottle or can in the 12 oz.
> size, my understanding is that either would require enhanced barrier
> performance for carbonation retention above that which PET by itself
> can provide.
> 
> All that the press release obliquely notes in this regard is that "The
> PETCAN(R) has multi-layer capability."  Without knowing more
> factually, I infer from this, and I have no other facts to go on, that
> they are indicating that one of the barrier materials, such as the
> nylon MXD-6 that was used in the Miller PET beer bottle, would be
> layered between the outer and inner layer of the plastic can.
> 
> If this is so, then the question arises of what such a multi-layer
> barrier PET can would mean for recyclers.  In a report which the
> Plastic Redesign Project I direct issued on the barrier bottles, we
> found that using the vendors' own data, and testing protocols that are
> appropriate for the industry, at the saturation levels that we would
> expect to see when barrier bottles are rolled out in the marketplace,
> the quality of recycled PET would deteriorate to the point that the
> new, promising and high paying bottle-to-bottle markets would be
> closed to us due to the yellowing MXD-6 causes.
> 
> I hope this answers Wayne's questions.
> 
> For anyone who wants to read more details about barrier issues, you
> can go on-line to: http://plasticredesign.org/files/execsumm.html
> 
>                                    Peter
> ______________________________
> Peter Anderson
> RECYCLEWORLDS CONSULTING Corp
> 4513 Vernon Blvd. Suite 15
> Madison, WI 53705
> Ph:    (608) 231-1100
> Fax:   (608) 233-0011
> Cell    (608) 438-9062
> email: anderson@no.address
> 
> 
> ----- Original Message -----
> From: "Wayne Turner" <WAYNET@no.address>
> To: <greenyes@no.address>; <anderson@no.address>
> Sent: Friday, January 03, 2003 1:37 PM
> Subject: Re: [GreenYes] /All PET "Can"
> 
> 
> Peter Anderson posted:
> 
> "According to a press release from Schotland, a Canadian firm, Water
> Investment Network, has developed an all PET beverage can,
> "PETCAN(R)", including a PET lid with a built in "easy-open"
> reclosable devise.  "Because the lid of the PETCAN(R) is made from the
> same PET material as the body, the package is claimed to be fully
> recyclable and evnrionmentally friendly," the press release asserts."
> 
> 
> And from where will the demand for all these 'fully recyclable and
> environmentally friendly' PET cans come?  In 2001 the US exported
> nearly half as much PET as it used domestically.  According to NAPCOR,
> existing domestic RPET plants are at 81.7% of capacity converting 670
> tons of PET bottles to RPET.  670 tons is equivalent to only 17.75% of
> total PET bottles on shelves in the US in 2001.  Additional PET
> bottles/cans can only result in lower recycling rates until virgin PET
> users begin to demand RPET as the preferred feedstock.  With the price
> of crude oil rising, maybe natural gas prices will rise to the point
> that the RPET flake will become an economically attractive alternative
> as a feedstock.  But, then, from where will the conversion capacity
> come?
> 
> Does anyone know the price differential between the amount of natural
> gas (ethene/ethylene?) to produce one ton of PET versus the price of
> one ton of RPET?
> 
> 
> B. Wayne Turner
> City of Winston-Salem
> Utilities Division
> phone: (336) 727 8418
> email: waynet@no.address
> 
> 
> 
> 
> 
> 
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