Effect of Pressure on CO2Transport in Polyethylene Terephthalate.

摘要

The CO2solubility,permeability and diffusion time lag in poly(ethylene terephthalate) are reported at 35 C and 65 C for CO2pressures ranging from 0.07atm to 20atm. The subatmospheric time lag and permeability measurements were made with a glass system at North Carolina State University while the measurements,using an identical polymer sample,between 1and 20atmospheres were made at The University of Texas with a metal system capable of tolerating gage pressures up to 30atmospheres. The measured solubility,permeability and time lag all show strong deviations from the well-known simple expressions for gases in rubbery polymers. The solubility isotherm is nonlinear in pressure and both theta and P are quite pressure dependent with each showing tendencies to approach low and high pressure asymptotic limits. These effects decrease as temperature increases and would be expected to disappear at or near the glass transition where the amorphous regions become rubbery. The importance of reporting the pressure levels used in transport measurements is emphasized for gas/glassy polymer systems where transport process do not follow linear laws. (Author)