An Apparatus for Research on Processes of Plasticization and Foaming of Polymeric Materials in Supercritical Media
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An Apparatus for Research on Processes of Plasticization and Foaming of Polymeric Materials in Supercritical Media E. O. Epifanova, S. A. Minaevaa, D. A. Zimnyakovb, c, V. K. Popova, and N. V. Minaeva, * a Institute
of Photon Technologies, Federal Science Research Center “Crystallography and Photonics”, Russian Academy of Sciences, Moscow, Russia b Saratov State University, Saratov, Russia c Institute of Precision Mechanics and Control, Russian Academy of Sciences, Saratov, Russia *e-mail: [email protected] Received April 5, 2020; revised April 14, 2020; accepted April 15, 2020
Abstract—An apparatus is described that allows studying various physical and chemical processes in the atmosphere of supercritical carbon dioxide at pressures of up to 25 MPa and temperatures of up to 100°C. The apparatus is based on a compact modular cylindrical high-pressure reactor with a diameter of 90 mm and a height of 100 mm with an internal volume of 14 cm3. It is equipped with eight optical ports, a system for measuring and adjusting the pressure and temperature, as well as a system for letting in and gradually reducing the pressure of the test medium. In addition, the reactor is equipped with two video cameras with a resolution of 1920 × 1080 pixels, which allow video recording of processes occurring in the reactor volume, which is synchronized with the pressure and temperature data recording system. The efficiency of the described apparatus is demonstrated by studying the processes of plasticization and foaming of polymer materials in the medium of supercritical carbon dioxide. DOI: 10.1134/S0020441220050103
Technologies based on the use of supercritical fluids (SCFs) are currently widely used to implement and study a variety of physicochemical processes [1]. The unique properties of supercritical carbon dioxide (scCO2) (at a pressure above 7.4 MPa and a temperature greater than 31°C), such as a high diffusion rate and the ability to act as a sufficiently strong non-polar solvent, are used, in particular, for highly efficient extraction of various chemical compounds, as well as impregnation and modification of amorphous and partially crystalline polymers. The opportunity to carry out the modification of scCO2 polymer materials that have been plasticized in the medium, which form porous micro- and macrostructures with specified parameters during foaming after depressurization, is of particular interest. By changing the parameters of the scCO2 medium it is possible to obtain highly porous (≥60 vol %) structures with different architectonics from biocompatible polymeric materials that can be used as bioresorbable matrices for biomedical applications [2]. The process of forming foamed polymeric materials using scCO2 usually involves several stages. At the first stage, a polymer sample is placed in a high pressure reactor at a given temperature. Carbon dioxide is then introduced into the reactor to the required pres-
sure, as a result of which plasticization of the polymer occurs. The reactor is then decompressed (
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