I have a part made of a thermoplastic material. When I heat it up and cool it down, the dimension of the part changes non-uniformly. Somehow the melted material tries to fill the sharper corners. So for example if there is a corner with a fillet of $r_1$ and wall thickness of $t_1$, after a high temperature experiment the part deforms to $r_2$ and $t_2$ where
I know it has to do with adhesion and capillary, but not knowing that much about chemistry jargon, I'm not able to find the right term for this phenomena. I would appreciate if you could help me know if this phenomena has a name and what parameters control this behaviour?