A particle in cell formulation for extrusion of fluoropolymers
The purpose of this work is to develop a mathematical model for paste extrusion of fluoropolymers obtained by dispersion polymerization and apply an Arbitrary Eulerian Lagrangian numerical method to predict the flow pattern of certain grades of fluoropolymers in shear flow. The mathematical model includes the effect of the extrusion aid on the flow patterns of fluoropolymers. The coupled equations of motion of the discrete and continuous phase in paste extrusion of fluoropolymers are solved using both continuum and discreet simulation methods. A combination between Non Equilibrium Molecular Dynamics and Continuous Simulation concepts is employed to model the particulate flow specific to fluoropolymers. The mechanism of increased strength in extrudates of fluoropolymers is explained based on molecular structure and shear flow through converging dies. A new concept of fiber formation probability is introduced and incorporated in the numerical analysis performed. The nature of the increased strength in fluoropolymers is explained based on a new concept of mechanically entangled fibers net. Extensive experimental studies on the extrudate strength are compared with numerical results on a qualitative and quantitative basis. Several aspects on the extrusion aid influence on the extrudate strength are analyzed. A new extrusion die design concept is presented and analyzed in terms of its influence on the extrudate strength. Several new concepts on die design are discussed and some suggestions for die manufacturers are presented.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:particles cell formulation extrusion fluoropolymers
Date of Publication:01/01/2003