Shrinkage Model for PET

[Simon Dunn]

Hi

I am looking at modelling PET in particular the shrinkage as part of a PhD, i am very new to the area and am finding it difficult to pinpoint key models and authors in the shrinkage field. Also where are the key institutions for such research?

I would be grateful if you could direct me to any shrinkage models and key authors. Id also be grateful for any advice on the topic.

Thankyou in advance for your help.
Regards
Simon

[Jorgen]

Sounds like an interesting topic. In this case, I assume that you are referring to the change in volume with temperature when you are saying "shrinkage". Is "shrinkage" a technical term by the way?

Unfortunately I don't know of any references on top of my head. I would do a comprehensive literature study...

- Jorgen

[Dilwyn]

What form is the PET you are considering? If it is injection moulded, then shrinkage is the difference between mould size and part size. Packing pressure, thermal expansion coefficient and crystallisation are key. In film (my area of competence), fibre and bottles, residual shrinkage is the change in length on heating a specimen then cooling, caused by partial recovery of stresses locked in during the cooling stage of manufacture. The shrinkage can be greatly reduced by a heat-setting step after stretching.
A very good starting point is the work of Professor Ian Ward at the University of Leeds.
Sorry about the delayed response - I don't come here often!
Dilwyn