Polybutadiene (PB) is an important synthetic rubber that readily oxidizes upon exposure to even low levels of atmospheric oxygen. The addition of a transition metal salt catalyst to PB markedly increases its ability to oxidize. This study presents results related to oxygen scavenging materials prepared from commercial polybutadiene doped with low levels of cobalt neodecanoate. The resulting membranes react with oxygen at room temperature, and they sorb up to 20 weight percent oxygen as a result.

This presentation will discuss the influence of preparation and reaction conditions on oxidation of 1,4-polybutadiene. Oxygen uptake is measured using an analytical balance and a non-invasive oxygen sensor based system, and the results from these two measurements techniques are compared. The effect of cobalt concentration, film thickness and oxygen partial pressure on oxygen uptake rate and amount were determined. Crosslinking was observed during the oxidation process, so the effect of crosslinking on oxygen uptake was also studied. Oxidation proceeds faster at higher oxygen partial pressure. Permeation tests using uncatalyzed and catalyzed 1,4-polybutadiene membranes show that O2 and CO2 permeability through such membranes decreases by more than two orders of magnitude as a result of oxidation.

Commercial 1,2 and 1,4-polybutadiene contain UV stabilizer packages that can be removed prior to preparing oxygen scavenging membranes. To remove the inhibitors, PB is first dissolved in toluene and then precipitated in methanol. Oxygen sorption experiments also demonstrate that oxygen uptake and oxidation rate depend on the number of purification steps (i.e., the extent of inhibitor removal). Oxygen uptake and oxidation rate are stable after a sufficient number of purification steps, suggesting that inhibitors can be removed to levels that do not influence oxygen scavenging properties.