The Use of Contact Angle Analysis to Examine the Degradation of Polymer Surfaces After Long Term Exposure to Hydrogen Peroxide in Pharmaceutical Isolators

The goal of this study is to examine the effect of hydrogen peroxide exposure on the surface properties of the plastic internal parts in pharmaceutical isolators, used in the aseptic liquid/powder filling processes. Hydrogen peroxide vapor (typically 400ppm H₂O₂) is commonly used as part of the decontamination process for isolators, and it is the effects of long term exposure to this environment on the plastic components inside the isolators that is being examined. A series of tests were performed in the Polymer Laboratory at Oregon State University that used an FTA 135 (First Ten Angstroms) surface goniometer to measure the contact angle of distilled water on plastic sheets of materials commonly used in isolators, before and after exposure to a hydrogen peroxide environment. The contact angle of distilled water on POM-C (polyoxymethylene copolymer [commonly referred to as Delrin™]), ultra-high-molecular-weight polyethylene (UHMWPE), and Teflon™ was measured before and after the plastic was immersed in 30 wt% hydrogen peroxide liquid, which was used to accelerate the testing. The contact angle results indicate that POM-C deteriorates over time when it is in contact with 30 wt% hydrogen peroxide. Visible degradation (the polymer changed color and developed surface bubbles) and a change in surface energy were observed in the POM-C samples. Apparently, the UHMWPE and the Teflon™ were not affected by the 30 wt% hydrogen peroxide. The surface degradation observed using the contact angle analysis were corroborated for a limited number of samples using a Scanning Electron Microscope (SEM). One goal of this preliminary study was to document that contact angle analysis, which is quick and inexpensive, is a legitimate technique for the determination of surface degradation in this application, which it appears to be.