Rheology of polydimethylsiloxane swollen with supercritical carbon dioxide

Gerhardt, Linda J.; Manke, Charles W.; Gulari, Esin

doi:10.1002/(sici)1099-0488(199702)35:3<523::aid-polb11>3.3.co;2-a

Cited by 37 publications

(73 citation statements)

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“…The influence of plasticizer is more pronounced in the lower shear rate range whereas at higher shear rate its influence diminishes due to the shear thinning effect of the polymer melt. A master curve was produced using a concentration-dependent shift factor a c similar to Gerhardt et al [40]. The viscosity of CA plasticized with 15 wt % TEC was taken as the reference curve.…”

Section: Foam Extrusion Testsmentioning

confidence: 99%

Extensional Flow Properties of Externally Plasticized Cellulose Acetate: Influence of Plasticizer Content

et al. 2013

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Elongational flow properties of polymer melts are very important for numerous polymer processing technologies such as blown film extrusion or foam extrusion. Rheotens tests were conducted to investigate the influence of plasticizer content on elongational flow properties of cellulose acetate (CA). Triethyl citrate (TEC) was used as plasticizer. Melt strength decreases whereas melt extensibility increases with increasing plasticizer content. Melt strength was further studied as a function of zero shear viscosity. The typical draw resonance of the Rheotens curve shifts to higher drawdown velocity and the amplitude of the draw resonance decreases with increasing TEC content. With respect to foam extrusion, not only are melt strength and melt extensibility important but the elongational behavior at low strain rates and the area under the Rheotens curve are also significant. Therefore, elongational viscosity as well as specific energy input were calculated and investigated with respect to plasticizer content. Preliminary foam extrusion tests of externally plasticized CA using chemical blowing agents confirm the results from rheological characterization.

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Section: Foam Extrusion Testsmentioning

confidence: 99%

Extensional Flow Properties of Externally Plasticized Cellulose Acetate: Influence of Plasticizer Content

et al. 2013

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“…The effects of CO 2 dissolution on viscoelastic properties were studied with capillary rheometers or extruders; for example, the shear rate dependence of viscosity was examined in the thinning regime. 1,2) These studies suggested that the dissolved CO 2 enhances the polymer chain motion (and effectively increase a distance from the glass transition point.) However, details of this effect on the linear viscoelastic relaxation and the equilibrium chain dynamics were not clarified.…”

Section: Introductionmentioning

confidence: 99%

Dielectric Behavior of cis-Polyisoprene in Carbon Dioxide under High Pressure

Inoue

Watanabe

Kihara

et al. 2007

J. Soc. Rheol., Jpn

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Dielectric measurement was conducted for cis-polyisoprene (PIP) in carbon dioxide (CO 2 ) at high pressures. CO 2 is dissolved in PIP more with increasing pressure, and this dissolution is expected to affect the chain dynamics. In our experimental window, the PIP chains having type-A dipoles parallel along their backbone exhibited the dielectric dispersion reflecting their global motion. This dispersion shifted to higher frequencies with increasing CO 2 pressure. Time -CO 2 pressure superposition was found to hold well, which suggests that the global motion of the chain is accelerated by CO 2 without any heterogeneity in space and along the chain backbone. The vertical shift factor (intensity shift factor) for this superposition gave the CO 2 concentration in PIP. The plasticizing capability of CO 2 evaluated from the horizontal shift factor (frequency shift factor) was found to be a little larger than that of tetradecane in the same range of concentration. No peculiarity was found for plasticizing ability of CO 2 even in the supercritical state (at a pressure of 10 MPa).

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“…In this context, the rheological and transport properties of solutions of polymer melts and physical blowing agents have attracted much attention. Accurate measurement techniques and determination of shift factors are the topics of several works [Han and Ma (1983a,b), Gerhardt et al (1997Gerhardt et al ( , 1998, Royer et al (2000Royer et al ( , 2001Royer et al ( , 2002, Kwag et al (1999), Lee et al (1999), Areerat et al (2002), ]. In most experimental studies (e.g., in measurements using capillary rheometry), the authors focused on the stationary viscosity of the melt as a function of the concentration of the blowing agent.…”

Section: Introductionmentioning

confidence: 99%

Viscoelastic properties of solutions of polystyrene melts and carbon dioxide: Analysis of a transient shear rheology approach

Handge¹,

Altstädt²

2012

Journal of Rheology

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In this work, the viscoelastic, thermal and diffusion properties of solutions of polystyrene melts and carbon dioxide (CO 2) were analyzed using plate-plate rheometry in the transient mode. The objective of this study was to evaluate a transient shear rheology approach for high viscosity polymer melts, to verify superposition principles for polystyrene/CO 2 solutions and to measure the glass transition temperature as a function of pressure and CO 2 concentration. Two different procedures of saturating polystyrene with carbon dioxide were applied, i.e. loading with the blowing agent below the glass transition temperature of polystyrene and at the measurement temperature. Stress-growth experiments in shear were performed in order to measure the transient viscosity of polystyrene/CO 2 solutions in the linear regime. A shift of the transient viscosity data to a mastercurve was applied in order to determine the shift factor of the viscosity and the average relaxation time. Our data indicate that the steady-state viscosity and the average relaxation time are proportional to the temperature-pressure-concentration shift factor a T,p,c within experimental scatter, and consequently a time-temperature-pressureconcentration superposition principle holds for polystyrene/CO 2 solutions. Whereas the viscosity of polystyrene strongly depends on the applied temperature and pressure, the elastic equilibrium compliance depicts only a weak dependence on temperature and pressure.

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Rheology of polydimethylsiloxane swollen with supercritical carbon dioxide

Cited by 37 publications

References 0 publications

Extensional Flow Properties of Externally Plasticized Cellulose Acetate: Influence of Plasticizer Content

Extensional Flow Properties of Externally Plasticized Cellulose Acetate: Influence of Plasticizer Content

Dielectric Behavior of cis-Polyisoprene in Carbon Dioxide under High Pressure

Viscoelastic properties of solutions of polystyrene melts and carbon dioxide: Analysis of a transient shear rheology approach

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