Simulation of thermal debinding: Effects of mass transport on equivalent stress

A simulation of thermal debinding in polymer removal from a PIM compact, based on integrated control volume finite difference and finite element methods, is proposed. Polymer pyrolysis, heat transfer, multi-phase fluid movement, as well as stress, deformation, and their interactions are simultaneously considered. The key phenomena of mass transport, i.e., the mass flux fields of total polymer, liquid polymer, polymer vapor, vapor diffusion, and vapor convection are analyzed. The effects of mass transport on the equivalent stress, which describes the distortion energy and is responsible for the yielding of a material, are investigated. The simulated results revealed that the equivalent stress, which might lead to failure of the compact, results mainly from the polymer liquid saturation gradient, i.e., the non-uniform distribution of polymer residue, which is attributed to the non-uniform flow of the polymer.