A predictive approach based on the Simha–Somcynsky free‐volume theory for the effect of dissolved gas on viscosity and glass transition temperature of polymeric mixtures

Abstract

The gas concentration and pressure effects on the shear viscosity of molten polymers were modeled by using a unified approach based on a free volume theory. A concentration and pressure dependent “shift factor,” which accounts for free volume changes associated with polymer‐gas mixing and with variation of absolute pressure as well as for dilution effects, has been herein used to scale the pure polymer viscosity, as evaluated at the same temperature and atmospheric pressure. The expression of the free volume of the polymer/gas mixture was obtained by using the Simha and Somcynsky equation of state for multicomponent fluids. Experimental shear viscosity data, obtained for poly(ε‐caprolactone) with nitrogen and carbon dioxide were successfully predicted by using this approach. Good agreement with predictions was also found in the case of viscosity data reported in the literature for polystyrene and poly(dimethylsiloxane) with carbon dioxide. Free volume arguments have also been used to predict the Tg depression for polystyrene/carbon dioxide and for poly(methyl methacrylate)/carbon dioxide mixtures, based on calculations performed, again, with the Simha and Somcynsky theory. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1863–1873, 2006

A gas-plastic elastomer that quickly self-heals damage with the aid of CO2 gas

“…2d). Some polymers, including PDMS, exhibit CO 2 gas plasticization 40–42 . However, our PDMS- x Na elastomer exhibits more distinct CO 2 gas plasticization.…”

Raman Line Imaging of Poly(ε-caprolactone)/Carbon Dioxide Solutions at High Pressures: A Combined Experimental and Computational Study for Interpreting Intermolecular Interactions and Free-Volume Effects

“…One of the most promising technologies for scaffold preparation is the CO 2 -foaming process, which can provide porous structures with carefully controlled morphology. − Among the attractive features of this processing technology, the most relevant is certainly its solvent-free, green-chemistry character. Gas-foaming is a complex process based on the nucleation and growth of gas bubbles (internal phase) dispersed throughout a polymer matrix (continuous phase) and its effective design requires specific information on the polymer/gas solution such as mass transport, − rheological properties, and thermodynamics . Moreover, the central role played by the specific interactions between the CO 2 molecules and the macromolecular chains has been recognized and requires in-depth study .…”

“…Gasfoaming is a complex process based on the nucleation and growth of gas bubbles (internal phase) dispersed throughout a polymer matrix (continuous phase) and its effective design requires specific information on the polymer/gas solution such as mass transport, 10−12 rheological properties, 13 and thermodynamics. 14 Moreover, the central role played by the specific interactions between the CO 2 molecules and the macromolecular chains has been recognized and requires in-depth study. 15 A number of investigations have recently appeared on mass transport and solubility of CO 2 in PCL 16−18 and the available data have been interpreted mostly by thermodynamic approaches describing the temperature effects on CO 2 solubility.…”

High-pressure rheological analysis of CO2-induced melting point depression and viscosity reduction of poly(ε-caprolactone)

“…Therefore, we have investigated the use of high-pressure rheology to detect the melting point of PCL under CO 2 (1-120 bar) by conducting an oscillatory rheometric study under high-pressure conditions. Furthermore, only few shear viscosity data over a narrow shear rate range are available for PCL in the presence of scCO 2 [51]. Hence, the aims of this study are to measure the T m depression of PCL through direct monitoring of the polymer viscoelasticity under CO 2 , and to study the effects of compressed CO 2 and N 2 on the shear viscosities of two grades of PCL of different molar mass (10 kDa and 80 kDa) under various temperature and pressure conditions, over a wide range of shear rates.…”