O. Muth et al., Investigation of sorption and diffusion of supercritical carbon dioxide into poly(vinyl chloride), J SUPERCR F, 19(3), 2001, pp. 299-306
The interaction of supercritical carbon dioxide (scCO(2)) with poly(vinyl c
hloride) (PVC) was systematically investigated. PVC films of 0.5 mm thickne
ss were treated with CO2 at pressures between 5 and 40 MPa, at temperatures
between 40 and 70 degreesC and soaking times between 0.5 and 7 h. The grav
imetric desorption data were kinetically and thermodynamically evaluated as
suming Fickian diffusion and the morphology changes due to the CO2 treatmen
t investigated by microscopic methods. The sorbed amount of CO2, q (q = g(C
O2)/g(polymer)) ranged between 0.03 (5 MPa, 70 degreesC) and 0.13 (15 MPa,
40 degreesC). The desorption diffusivities, D-d, were in the order of 0.1 x
10(-11) m(2)/s and decreased with decreasing amounts of CO2. In contrast,
the sorption diffusivities, D-d, were markedly higher and varied between 0.
7 x 10(-11) and 2.5 x 10(-11) m(2)/s (20 MPa, 40-70 degreesC). The CO2 trea
tment changed the polymer chain structure. macroscopically visualized by th
e film opaqueness and by the density decrease to 1.05 g/cm(3). Microcellula
r structures were not detected. (C) 2001 Elsevier Science B.V. All rights r
eserved.