Infrared spectroscopic study of polymers exposed to ethylene oxide

Fourier transform infrared spectroscopy has been used to study thin polymer films exposed to ethylene oxide (EO). The i.r. technique represents a new way of studying this subject. The polymers studied were poly(vinyl chloride), polyethylene and polystyrene. They were exposed to EO, either in a small commercial EO-sterilizer which uses pure EO and operates at subatmospheric pressure, at a temperature of 37 or 55°C, or under experimental laboratory conditions. The absorption and diffusion of EO in the polymers was studied. Potential reaction products, such as ethylene glycol and ethylene chlorohydrin, were looked for but could not be traced. The detection limit of the method was 1 ppm (μg/g) EO. Typical spectra of the polymer films, before and after exposure to EO, are shown. Diffusion coefficients for poly(viny) chloride) and polyethylene have been calculated.