Learning Forum

[nick5990]

Hi, I've been using CES Edupack 2020 as part of University course to aid with materials selection

Using the Level 2 database, with "Price GBP / Kg " on Y axis vs "Recycle fraction in current supply %" on X axis, I obtained the below chart, and noticed the PET is above 20% for around £1 / kg.

[Janos Plocher]

Hello nick5990
Thank you for your question and pointing this out. We don see this in the latest version of EduPack (2022R1), as you can see in the image attached. As shown, the value for the recycle fraction ranges between 17.3-19.1% for PET at Level 2. Thus, I would kindly invite to to upgrade to the most recent release.
Just for your understanding: Level 3 databases are updated regularly to match industry changes, while Level 1/2 databases are only updated yearly to allow courses to teach with the same data over a whole academic year - so there can sometimes be discrepancies between data in L2 and L3 as a result.
I hope this helps.
Best János

[nick5990]

Hi Janos, I wasn't pointing out a discrepancy (the differences just appear to be due to detail in L2 and L3 databases in my opinion.
It is not possible for me to update CES 2020 to a more recent version as its not been made available for the module I'm studying. Hence please refer to CES Edupak 2020 for this thread.
Please see my previous post re amorphous/ crystalline question which may have been overlooked

[Janos Plocher]

Hi nick5990,
If you would like to include semi-crystalline PET, than you must include the optical properties 'translucent' in your limit stage. This means the material transmits little diffuse light (see science note for more details) and may - depending on the application - also be considered for 'optical' (partially light-resistant) purposes. There are of course specific manufacturing steps that can be taken to make semi-crystalline PET more transparent, but they are not considered here.
You have of course also the option to limit your results by pre-selecting the material family you are looking for, i.e. thermoplastic amorphous or semi-crystalline, but only the former PET variant is considered 'optical quality'.
I hope this answers the question. If not may I kindly ask you to elaborate. Thanks!

[nick5990]

Hi j_p, thanks for info re "translucent" - I didn't think to check the definition, and that's valuable what you posted. I'm only interested in "transparent" and "optical".
Re amorphous plastics such as amorphous PET and amorphous PMMA - are these considered solid?