Simulation of anisotropic diffusion under large deformations in polymer blends

Abstract

AbstractBlending polymers with different properties is a popular method to customize the behavior of a polymer material. For this, in some cases, the materials are mixed in molten form. At high temperatures, this usually yields a single phase, consisting of both the polymers. At lower temperatures, the blend often starts to decompose into two or more phases, which can yield a complex microstructure. One way to control this resulting structure, is to treat the cooling melt mechanically, whereby lamellar patterns are often observed. Performing computer simulations can help to understand the behavior of the mixture and thus help to be able to better control the microstructure of the polymer blends in the manufacturing process. This can improve the performance of the material.Following a well‐known approach, a phase‐field determines the material distribution in a domain, representing the microstructure of the polymer blend. Here, the Cahn‐Hilliard equation describes the evolution of the mentioned phase‐field, starting with a random initial distribution. The domain is strongly deformed to force a rearrangement of the structure while the blend is decomposing, thus a large deformation framework is considered, cf. [1]. The decomposition process is investigated, using simulations for different deformations and by comparing them to a simulation in the classical undeformed case. Anisotropic diffusion occurs in the deformed domains, which yields regular patterns.