Hello,
I am trying to estimate the thermal expansion of a semi-crystallin polymer (PEEK) with different degrees of crystallization. I couldn't find any rescources on this topic. Did somebody also encounter this specific problem? I'm just trying to get some orientation on how the degree of crystallinity effects thermal expansion to model it with isotropic material data.
Kind regards!
We've had this issue with the expansion of semi-crystalline to crystalline PEEK before, while in a stainless-steel insert molding. We overcame it with empirical testing and tweaks to the molding cycle, but the modelling required an X-ray or similar image of the crystallite distribution over the piece, which allowed us to adjust the molding cycle to improve the crystallinity and crystallite size to allow the thermal expansion to match that of the stainless steel insert.
Thank You for Your answer! I don't really have the capacities to run a empirical test or a special experiment. I've searched for data regarding this topic, to estimate the expansion with relation to crystallinity qualitatively, and didn't find any. I found data for mechanical properties, but this one is tough.
If you have access to Ansys's material modules, they have a homogenised version of the material properties which includes a thermal expansion coefficient, vary it by a little up or down to see how it matches pre-existing data or how it fits your model. The other option is to contact Dr Jorgen Bergstrom (https://www.researchgate.net/profile/Jorgen-Bergstrom) @JorgenBergstrom for advice.
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