Supercritical Carbon Dioxide Interaction with Polymeric Materials: Desorption Diffusion Coefficient Measurements

摘要

Chemical-polymer compatibility is an important criterion in the development of solvent-based extraction and cleaning systems for removal of toxic contaminants from polymeric surfaces. The potential degradation of polymer properties and performance is especially critical for sensitive equipment cleaning, decontamination, and extraction. The candidate cleaning fluids for sensitive equipment include fluorinations and supercritical fluids. An overall material evaluation strategy has been developed for evaluating the degradation of polymer properties by exposure to supercritical fluids. The initial evaluation involves the measurement of the sorption and desorption diffusion coefficients in a spectrum of polymer compositions. The objective was to characterize the complete desorption process by the continuous measurement of the entire diffusion process. Another purpose of diffusion coefficient measurements was to provide an estimate of the time required for each material to completely adsorbs all of the carbon dioxide cleaning fluid and return the material to the original unplasticized condition. These measurements and calculations provided the high data density required to calculate a low concentration Fick's Law diffusion coefficient and equation for the extrapolations. The composition spectrum selected contains hydrogen bond donor, hydrogen bond acceptor, dipolar, and non-polar polymer structures. Over 20 thermoplastics and elastomers were studied with supercritical carbon dioxide.