In situ FTIR measurement of carbon dioxide sorption into poly(ethylene terephthalate) at elevated pressures

Abstract

Knowledge of the sorption rate and solubility of CO 2 in polymers are of great importance for developing technologies utilizing high-pressure and supercritical CO 2 -assisted processes. Many conventional techniques for measuring gas sorption have inherent complications when used at elevated pressures. In this work, we demonstrate the use of near-IR spectroscopy as an accurate method to measure CO 2 sorption kinetics and solubility in PET at elevated pressures. Sorption kinetics and solubility are measured at 0, 28, and 50°C between pressures of 57.1 and 175.2 atm. Both initially amorphous and initially partially crystalline samples of PET are studied, and the effects of the initial crystallinity are determined. In addition, the effects of CO 2 processing on the final crystallinities of our samples are measured. Crystallization was induced in PET at 28 and 50°C over the range of pressures studied. However, at 0°C, no detectable crystallization occurred in PET, even in the presence of high pressures of CO 2 . The method demonstrated in this work could easily be extended to directly measure CO 2 sorption in other polymers.

Drug loading of polymer implants by supercritical CO 2 assisted impregnation: A review

“…Whereas the chain mobility is restricted below the T g , it increases above the T g which allows higher CO 2 sorption and swelling [76,77]. This effect can be counterbalanced by the decrease of CO 2 density with temperature under isobaric conditions [78][79][80] and by the CO 2 -induced recrystallization in semicrystalline polymers [81,82]. Nevertheless, if the temperature approaches the melting temperature of semi-crystalline polymers T m the crystals melt which increases the amorphous regions in the polymer and so the CO 2 sorption and the swelling [83].…”

Sorption and diffusion of dense carbon dioxide in a biocompatible polymer

“…Similar behavior has been reported by other authors [14,21,22] with distinct polymers. Kazarian and co-workers [14,23] have demonstrated spectroscopically the existence of specific interactions between carbon dioxide and various polymers, most probably of Lewis acid-base nature. This author has also pointed out the exothermic nature of this interaction.…”

“…The use of a quartz-crystal microbalance and a gravimetric method or a barometric method are the most commonly used [11,12]. Transmission IR spectroscopy has also been used to measure the sorption of polymers [13,14,24]. In regards to measurements on polymer swelling, the direct observation of the sample's dimensions is widely used [7].…”

Quantifying Polymer Swelling Employing a Linear Variable Differential Transformer: CO2 Effects on SBS Triblock Copolymer

“…CO 2 solubility in polymers has often been determined by measuring gas sorption [3] by means of gravimetry, [4,5] and by spectroscopic methods. [6] Gas solubility has also been quantified by direct observation of polymer swelling. [5,7,8] Ender developed a linear variable differential transformer (LVDT) method to measure o-ring swelling.…”