Measurement of Shear Viscosity and Solubility of Polystyrene Melts Containing                 Various Blowing Agents

Choudhary, Manoj K.; Delaviz, Yadi; Loh, Roland; Polasky, Mark E.; Wan, Chengpeng; Todd, David B.; Hyun, Kun S.; Dey, S. K.; Wu, Fei

doi:10.1177/0021955x05059036

Cited by 9 publications

(4 citation statements)

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“…The presence of gas inside the polymer can reduce its viscosity, thus allowing the processability of the polymer at lower temperatures and pressures. This is an advantage particularly for biodegradable polymers, which are thermally sensitive and have narrow processing windows .…”

Section: Introductionmentioning

confidence: 99%

Foam injection molding of poly(lactic) acid: Effect of back pressure on morphology and mechanical properties

Volpe

Pantani

2015

J of Applied Polymer Sci

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Foam injection molding is a processing technology applied to produce a plastic part of a well‐defined shape, containing a significant fraction of voids and thus consuming less material without sacrificing mechanical properties. This technology is particularly interesting for biodegradable polymers and in particular for poly(lactic acid), PLA, since it can be adopted to save material and to avoid thermal degradation due to its high viscosity at high shear rates, which requires high temperatures in traditional injection molding process. In this work a traditional injection molding machine, modified just in the cylinder to allow the gas injection, was adopted to obtain foam injection molding of a PLA grade. In particular, the effect of back pressure on foaming was assessed. Back pressure is the pressure imposed at the back of the screw when it is returning back to prepare a new amount of material to be injected (batching phase) and thus is particularly relevant in the formation of the polymer−gas mixture. It was shown that on increasing the back pressure the percentage of foaming agent inside the injection chamber is smaller, and thus foaming is less effective. The obtained samples were characterized as far as density and mechanical properties are concerned and it was found that it was possible to reduce the density of about 25% without a significant loss of mechanical properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42612.

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Section: Introductionmentioning

confidence: 99%

Foam injection molding of poly(lactic) acid: Effect of back pressure on morphology and mechanical properties

Volpe

Pantani

2015

J of Applied Polymer Sci

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“…If a blowing agent is injected and dissolved into a polymer melt, a decrease of viscosity can be observed. 1,7,13,14,26,27 Gerhardt et al 6 applied Doolittle's 28 free volume theory to describe the viscosity reduction to be caused by an increase in free volume and therefore increased mobility of molecular segments. This lowered viscosity is accompanied by a reduction of the glass transition temperature (T g Þ, which has been observed to be in linear correlation to pressure increase.…”

Section: Rheology Of Blowing Agent Loaded Polymer Systemsmentioning

confidence: 99%

“…29 This allows processing at lower temperatures compared to the extrusion of pure polymer. Several studies explored blowing agent-induced viscosity reduction, 1,7,13,14,26,27 notably Gerhardt et al investigated PDMS with CO 2 and concluded that a higher mass fraction of blowing agent results in a lower viscosity, but does not result in a changed shear rate induced slope of the flow curve. 2 This allows for the application of viscoelastic scaling models and construction of a master curve.…”

Section: Rheology Of Blowing Agent Loaded Polymer Systemsmentioning

confidence: 99%

Viscosity measurement of polypropylene loaded with blowing agents (propane and carbon dioxide) by a novel inline method

Vincent

Langlotz

Düngen

2019

Journal of Cellular Plastics

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Decreased viscosity due to the influence of blowing agent in thermoplastic polymer melts is a key issue for understanding the process of foam extrusion. In a process for direct foam extrusion, a novel approach for inline viscosity measurement of single-phase systems in single screw extruders is used to experimentally evaluate a viscosity decrease. Two blowing agents (propane and carbon dioxide) are tested for their effect on the viscosity of a polypropylene melt. While mass fractions of blowing agent below [Formula: see text] show little to no effect in regard to viscosity reduction compared to a pure polymer melt, a mass fraction of [Formula: see text] already results in significantly decreased viscosity values. While melt temperature influences the viscosity of the polymer melt, measurements show no significant additional effect in regard to a lowered viscosity of a single-phase system of polymer and fully dissolved blowing agent.

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“…Furthermore, it was shown that the pressure coefficient of polystyrene does not depend on the degree of branching and not significantly on the tacticity, either [Pantani and Sorrentino (2005)]. Most previous works on the rheology of solutions of a polymer melt and a blowing agent were devoted to shear flows [Royer et al (2001), Choudhary et al (2005), ].…”

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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Measurement of Shear Viscosity and Solubility of Polystyrene Melts Containing Various Blowing Agents

Cited by 9 publications

References 0 publications

Foam injection molding of poly(lactic) acid: Effect of back pressure on morphology and mechanical properties

Foam injection molding of poly(lactic) acid: Effect of back pressure on morphology and mechanical properties

Viscosity measurement of polypropylene loaded with blowing agents (propane and carbon dioxide) by a novel inline method

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

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