Study of thermal decomposition of a polyisobutylene binder by molecular dynamic simulations

Fugitive binders are a group of polymeric materials used in slurry powder-based manufacturing processes. These are often removed at an intermediate temperature before sintering of the powder per-form. Complete removal of binders is usually essential to ensure high quality components after sintering. This requires a clear understanding of the decomposition mechanisms of binders. Polyisobutylene (PIB) is a promising binder for the fabrication of titanium matrix composites via slurry powder metallurgy. Here, the thermal decomposition mechanisms of PIB were investigated using molecular dynamics (MD) to determine the decomposition mechanisms and the optimum debinding conditions. A MD code, MD_REACT, was used to simulate chemical reactions such as bond breaking and forming during the simulation. This code is coupled with a commercially available MD package (Discover95). The current model consists of a single chain PIB simulated at different temperatures for 5 ps to investigate the influence of temperature on the degradation behaviour and the yield of volatile species. Interactions of degraded products were also analysed. Likely degradation products from PIB were identified and compared with experimental findings from mass spectrometry analyses.