Spectroscopic analysis and in situ monitoring of impregnation and extraction of polymer films and powders using supercritical fluids

Abstract

A range of vibrational spectroscopic techniques are used to monitor supercritical fluid extraction and impregnation of polymers. Impregnation processes of this type show potential as alternative apporaches to the synthesis of polymer based catalysts and new materials. Methods have been devised using conventional Fourier transform infrared spectroscopy for real time monitoring of the extraction and impregnation of polyethylene films using an organometallic complex, CpMn(CO)3 (Cp = η5 − C5 H5) as a spectroscopic probe. Both low and high density powdered polyethylene may be impregnated using supercritical carbon dioxide. The resulting materials are analysed using FTIR photoacoustic spectroscopy, diffuse reflectance infrared spectroscopy and FT Raman spectroscopy to probe both the impregnated bulk of the polymer and surface‐coated material. © 1994 John Wiley & Sons, Inc.

Critical ReviewAnalytical Extraction of Additives From Polymers

“…At 70 °C, the effect of increased pressure (solubility) on the extraction curve was to increase the slope of the initial steep ln(m/m 0 ) curve and increase the slope of the linear portion of the graph, i.e., increased extraction rate. The 38 A method for direct observation of the extraction process in real-time is described by Howdle et al 39 using an organometallic complex. The IR absorption bands are sensitive to the environment, and therefore a shift in the spectrum occurs when the complex is extracted from the polymer.…”

High‐pressure phase equilibria for a styrene/CO2/polystyrene ternary system

“…During the past two decades, supercritical fluid (SCF) techniques have received increasing attention for the purification and extraction of chemicals, 1–2 including the devolatilization3–6 and impregnation 7–8 of polymers. In polymer processes, a variety of volatile impurities, such as monomers, solvents, byproducts, and catalysts, are involved.…”

Recent Developments in Polymer Processes

“…On depressurization, the CO 2 flows out of the polymer matrix, leaving the solute trapped in it [112]. There are two different methods of supercritical fluid impregnation of additives into polymer products.…”