Coextrusion of biodegradable starch-based materials

Multilayer coextrusion offers an interesting way of incorporating the properties of several biodegradable polymers, in a single processing operation. However, there are certain limitations due to flow phenomena that occur within the coextrusion die, affecting the functionality and quality of the product. The most serious problems are encapsulation and interfacial instabilities. The reason for their occurrence is attributed to large stresses at the interface of two layers, due to viscosity and elasticity differences, and to unproper die geometry. The simulation of coextrusion flows is a unique way to quantify the problem and an aid for die design.