MULTISCALE MODEL FOR POLYMER CRYSTALLIZATION - II - SOLIDIFICATION OFA MACROSCOPIC PART

In part I of this paper, we presented two efficient front tracking met hods to simulate the growth of a spherulite within an imposed temperat ure field. In this second part we present a method that predicts the f inal microstructure in a macroscopic part by coupling these front-trac king techniques with (a) a stochastic model for the nucleation of indi vidual spherulites, (b) a cellular model for spherulite impingement an d solid fraction evolution and (c) a Finite Difference Method (FDM) fo r latent heat release and heat diffusion. The method tracks the physic al phenomena on several length scales: a coarse grid for the heat diff usion, a fine grid for solid fraction evolution and a very fine grid f or the shape of the individual spherulites and the lamellae within the m. To our knowledge this is the first time that a fully coupled multis cale model has been applied to the solidification of polymers which gi ves realistic microstructure evolution, orientation of the different l amellae within spherulites and maps of the solid fraction and temperat ure fields during solidification. The model provides us with a quantit ative predictive tool that can be used to optimize industrial processe s.