Oxygen scavenging styrene-butadiene-styrene block copolymer films for barrier applications
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This dissertation discusses the oxidation behavior of reactive membranes that were produced by solution casting and by melt extrusion. These films, containing styrene-butadiene-styrene (SBS) block copolymer that undergoes catalytic oxidation, are of potential use as an oxygen scavenging polymer (OSP) for barrier applications. A thin film kinetic model was developed to ascertain reaction parameters that were used to describe thick film oxidation behavior. Ultimately complex structures containing these scavengers need to be produced via melt-extrusion. Therefore, processing conditions were established to ensure that melt-processed films have the same oxidation kinetics and capacity as those prepared by solution casting. Blends containing a non-reactive styrene phase and an oxygen-scavenging SBS phase were extruded and, by uptake and permeation experiments, their oxidation behaviors were monitored. The flux behavior and time lag extension as a function of oxygen pressure, film thickness, SBS scavenger and photoinitator contents were measured and compared to the theoretical model. The permeation behavior of the reactive blend films containing SBS showed that time lags can be extended via an oxidative mechanism and barrier properties be improved compared to traditional packaging membrane of native polystyrene.