Simulating the Oxidation of Polypropylene Using a Reactive Forcefield

Oxidation of organic materials is a problem for seals and membranes in many environments. Any particular instance of a chemical reaction is fast with purely local effects. Over longer times, the cumulative effect of many reactions results in large changes in average stress, strain, and other macroscopic properties of the sample. We have had some success in developing constitutive models for rubber, which connect the topology of the network with the observed stress during aging under strain. As the next phase of the project, we have performed simulations using a reactive forcefield to examine the atomistic changes during oxidation. Results will be presented for polypropylene and compared with experimental data for labeled samples undergoing oxidation.