A finite element model of spinodal decomposition in a power-law fluid in the extruder cooling die has been developed to investigate the effects of different parameters on fibre formation and alignment. The model makes use of the Cahn-Hilliard equations with a thermodynamic potential and numerical approximations to simulate local compositions in the separated state. The constitutive model is calibrated towards extrusion-relevant strain rates and temperatures by using a combination of rheometry techniques. The simulations show that the effect of decreased wall cooling has a limited effect on fibre development. Instead, decreasing the die width or increasing the die length can be used somewhat interchangeably to achieve fibre formation at the die exit. Viscosity also seemed to influence fibre formation in the outer viscous regions of the die by yielding comparably finer lamellar structures. The local composition of fibres also varied across the die, which may indicate differences in fibre consistency.
Sweden's Innovation Agency Vinnova is gratefully acknowledged for partial funding of the present work through the “Swedish Plant-based Meat Analogues – Generation 2” project, grant no. 2021-03556.