Day 21: Nov. 7th, 2009

March 1, 2010

After sending out several emails to contacts in different organizations (who wish to remain anonymous), I received the following information about non-bottle PET recycling. Hopefully you will find this information as valuable as I did in my journey to discover why PET clamshells, blisters, trays and components are not recycled in most American communities.

Quick answers:

  1. Including blister packs into PET bottle recyclate is unlikely to be good idea;
  2. Clear PET trays might be technically okay to be mixed in with PET bottles – but there is a sorting problem due to PVC;
  3. PET trays/clamshells/blister packs could be sorted out of the residual mixed plastics waste to make an rPET grade – although this may prove to be more restricted in markets than bottle recyclate.

PET types

Blister packs that aren’t PVC generally use a copolymer of PET called PET-G or PETG. This is softer and tougher than standard PET and can’t crystallize, so is used for some PET films and thin sheet applications because the manufacturing is easier (even though the material is a bit more expensive).  Some clamshells and trays use PET-G, but most will use standard PET identical to that used for bottles. All ovenable frozen food trays use crystallized PET as they need to stay rigid at high temperature – this is chemically identical to bottle grade, but most frozen food trays are pigmented anyway?

PET-G can be a problem in PET recycling. A little bit probably would never be noticed, but if significant sources of PET-G were going to be used as feedstock for any particular process, this would have to be fully tested in trials by the re-processor and the end-users – recyclate for use in bottles (made by injection stretch blow molding) might not be able to accept much PET-G without quality problems, but a recyclate intended for trays or clamshells (made by sheet extrusion and thermoforming) might be fine.

PVC Issue

Getting PET packages recycled also depends on the confidence and cost of being able to extract the PET from the commingled plastics without excessive PVC contamination, which degrades at PET processing temperatures (causes yellowing, black specks and may affect food-contact status)

Since clear PVC is widely used in these sort of packages as well as PET and the two are visually indistinguishable except by inspection of the plastics code (if present) then manual pre-sorting and final checking won’t be feasible based on container shape as it is for bottles. Therefore the automatic sorting would have to start from a very high contamination level– this increases the difficulty of getting to a low enough level of PVC content.

With PET bottle recycling, it is already a little difficult to keep PVC low enough, as PVC gets into the bottle stream anyway in the form of labels and cap liners – if you tried to include trays etc, then only a few PVC packs would need to sneak through the sort process to downgrade a batch.

Hence, recyclers are hesitant to include PET clamshells, trays etc with sorted PET bottles because they might end up with lower incomes despite the higher volumes.

All this means to me that it is more sensible to try to get PET clamshells and trays from the mixed plastics fraction (after already removing bottles) and finding a market for that quality of rPET, rather than trying to sort bottles and clamshells/trays together. This is the approach being tested by WRAP (Nextek are running a project for them).

Okay…so based on this insight, it is more feasible to create a new end-market for mixed rigid plastic material than to try and integrate our PET packages into the existing PET-bottle recycling infrastructure…

That’s all for today folks; I think we should all let this information sink in. Tune in tomorrow for more discoveries about recycling in America!