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Decision-making when it comes to PET
Packaging consultant Sterling Anthony looks into the diverse range of packaging solutions that PET can offer.
Thanks mostly to deposits on beverage bottles, PET is the most recycled plastic. Still, a sizeable tonnage of PET in all forms is landfilled. Therefore, choosing PET is not an automatic ‘pass’ to sustainability – there’s also its petrochemical origins to consider.
Ironically, the existing recycling infrastructure for PET – modest though it may be – is part protection against competition from bioplastics, particularly PLA, polylactic acid. Bioplastics’ resemblance to PET can cause it to be misplaced into the PET recycling stream and contaminate it.
There’s probably not a packaging professional who’s unaware that polyethylene terephthalate (PET) dominates the categories of non-alcoholic beverages. What’s less diffused is awareness that PET issues, for better or for worse, extend beyond beverages and carry ramifications for many consumer packaged goods. It requires that potentially impacted packaging professionals have a fundamental knowledge of the properties and applications of PET and of its impending developments.
Reciting the alphabet
- By family, PET is a polyester; a polymer formed by the reaction of an acid and a base, in this case terephthalic acid and ethylene glycol. The basic properties of PET can be modified by changing the number and proportions of acids and bases as well as by varying the parameters of the manufacturing process.
- APET (amorphous polyethylene terephthalate)** has high clarity, the closest to glass of any polymer. Amorphous describes an arrangement of molecular chains that is random – rather than in structured alignment – which accounts for its clarity.
- PETG (polyethylene terephthalate glycol)**, being amorphous, also has clarity. The addition of the modifying glycol imparts increased melt strength.
- CPET (crystallised polyethylene terephthalate) has undergone crystallisation – a structured alignment of the molecular chains. Typically opaque it has increased temperature tolerance, from freezer to oven temperatures.
Decision making
These examples show how the term ‘commodity’ is misapplied in reference to packaging material: no matter how seemingly standard a material, modifications, present or potential should be considered. The objective should always be to optimise the match between material properties and end-user applications.
A straightforward part of the decision might be deciding on:
- APET because you want the product presented in glass-like clarity
- PETG because you require deep-draw thermoforming
- CPET because you need ‘microwavability’.
It’s improving upon that basic decision that helps justify your salary. In short, you should strive for innovation, not just for its own sake, but aligned with the core persona of your brand.
If the application involves a rigid primary package, there’s a modest probablility that PET or one of its copolyers deserves to be considered.
That generalisation, however, shouldn’t be misinterpreted as advocating PET, for in many possible scenarios, PET isn’t the ideal choice.
Remember rPET
rPET (recycled polyethylene terephthalate), for all intents and purposes, comprises reprocessed beverage bottles. Packaging applications – versus textiles, carpeting, strapping etc – are overwhelmingly bottles and thermoform sheets.
Assuming that recycled materials can produce environmental benefits, equally important is that they can yield commercial benefits. rPET should make good business sense. Achieving that aim requires three interrelated things:
- It adds to the packager’s reputation as environmentally conscientious.
- The reputation favourably influences consumer purchase behaviour.
- There must be no sacrifice in quality, performance, aesthetics or convenience.
Implied in all of this is an established package research and development framework. Also needed is a communications strategy that effectively informs the consumer of the recycled nature of the package. A complicating issue is whether to divulge the percent of rPET within the package.
Coextrusion technology allows rPET to be combined with virgin content, even sandwiching it when direct product contact is undesirable. For example, if the label announces 35% recycled content, does it expose itself to one-upmanship by another that boasts a greater percent content?
Recyclability has not shielded bottled water from withering environmental attacks. Lately, bottled water has drawn safety concerns regarding the advisability of leaving it inside a hot car or other locations of elevated temperatures. The feared result is the leaching of carcinogenic agents from the package into the water.
The lesson here is that a higher profile material is a natural target of detractors, wrong-headed though some might be. That’s worrisome enough for packagers, but in this era of instant communications, such attacks can quickly become viral, and indict other packaging through guilt by association.
In all, staying abreast of the PET front is the best insurance that PET projects don’t turn into PET problems.
Sterling Anthony is a packaging consultant, advising companies and governments on appropriate packaging solutions.
Copyright 2009 Summit Publishing Company. All rights reserved. This article from the July 2009 issue of Packaging World Magazine (www.packworld.com) is reprinted by permission of Summit Publishing Company. Packaging World is a registered trademark of Summit Publishing Company. www.greenerpackage.com
Sterling Anthony website: http://www.pkgconsultant.com/index.htm
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