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Density measurement of polymer/CO 2 single‐phase solution at high temperature and pressure using a gravimetric method
Author(s) -
Funami Eita,
Taki Kentaro,
Ohshima Masahiro
Publication year - 2007
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.26513
Subject(s) - gravimetric analysis , polymer , materials science , dissolution , phase (matter) , analytical chemistry (journal) , lower critical solution temperature , polymer chemistry , thermodynamics , chemistry , copolymer , composite material , chromatography , organic chemistry , physics
Abstract The densities of two polymer/CO 2 single‐phase solutions, poly(ethylene glycol) (PEG)/CO 2 and polyethylene (PE)/CO 2 , were measured at temperatures higher than melting temperature of the polymer under CO 2 pressures in the range 0–15 MPa using a newly‐proposed gravimetric method. A magnetic suspension balance (MSB) was used for the density measurement under the high pressure CO 2 : A thin disc‐shaped platinum plate was submerged in the considered polymer/CO 2 single‐phase solution in the MSB high‐pressure cell. The weight of the plate was measured while keeping CO 2 pressure and temperature in the sorption cell at a specified level. Since the buoyancy force exerted on the plate by the polymer/CO 2 solution reduced the apparent weight of the plate, the density of the polymer/CO 2 solution could be calculated by subtracting the true weight of the plate from its measured weight. Experimental results showed that the density of PE/CO 2 solution increased with the increase of CO 2 pressure and the density of PEG/CO 2 solution decreased with the increase of CO 2 pressure. To differentiate the effect of CO 2 dissolution in polymer from that of mechanical pressure, the density of polymer/CO 2 solution was compared with the density of neat polymer under the given mechanical pressure, which was calculated using the Sanchez–Lacombe equation of state and Pressure–Volume–Temperature data of the polymer. The comparison could elucidate that the dissolution of CO 2 in polymer reduced density of both PEG/CO 2 and PE/CO 2 systems but the degree of CO 2 induced‐density reduction was different between two polymer/CO 2 systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007