Mechanical Measurement of the Plasticization of Polymers by High-Pressure Carbon Dioxide

Al-Enezi, Salah; Hellgardt, Klaus; Stapley, A.G.F.

doi:10.1080/10236660701223790

Cited by 8 publications

(7 citation statements)

References 24 publications

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“…However, such general plasticization effect does not identify the gas permeability dependence on upstream penetrant pressure. As a matter of fact, several experimental papers reported that polymer T g decreases in the presence of CO 2 (or other substances) ,, and that the mechanical properties also change. − These effects are progressively detected as CO 2 is sorbed at increasing pressures: no clear onset may be associated with a specific pressure value, in clear contrast to the idea of a threshold “plasticization pressure”.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

110th Anniversary: Gas and Vapor Sorption in Glassy Polymeric Membranes—Critical Review of Different Physical and Mathematical Models

Minelli

Sarti

2019

Ind. Eng. Chem. Res.

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The analysis and modeling of the sorption behaviors in glassy polymers, of gases and vapors in particular, is of crucial relevance for a variety of different applications. Due to the peculiar behaviors associated with the nonequilibrium character of polymer glasses, different approaches have been used so far to describe gas solubility, whose dependence on penetrant pressure or activity shows a broad spectrum of experimental behaviors. In this work, three commonly used and completely different approaches (the Dual Mode Sorption (DMS), based on simultaneous adsorption and solubility; the Guggenheim–Anderson–de Boer (GAB) model, considering only adsorption; and the Nonequilibrium Thermodynamic model for glassy polymers (NET-GP), considering only solubility) have been critically reviewed and compared. The screening inspects the model ability to represent the different features shown by solubility isotherms in glassy systems, as well as their ability to provide reliable predictions with parameter values consistent with the underlying physical models. Finally, physical consistency issues have been also considered whenever appropriate. The analysis reveals that DMS and GAB describe well various experimental sorption behaviors, while they fail in representing other cases, such as those shown by the S-shaped isotherms of alcohols or those due to penetrants in supercritical conditions. More remarkably, both models reveal serious physical inconsistencies in the application to sorption–desorption hysteresis. Conversely, the NET-GP approach, combined with a Lattice Fluid model (NELF) shows a better predictive power, as it can naturally account for the S-shaped isotherms, and it is also physically consistent with the behavior observed in sorption–desorption hysteresis cycles.

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Section: Theoretical Backgroundmentioning

confidence: 99%

110th Anniversary: Gas and Vapor Sorption in Glassy Polymeric Membranes—Critical Review of Different Physical and Mathematical Models

Minelli

Sarti

2019

Ind. Eng. Chem. Res.

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“…Figure 7 illustrates these incidents of bubble formation for all the operating conditions. The results also compared with the reported values of plasticization of PS by high-pressure CO 2 [20]. It can be clearly seen that bubbles form only when the polymer has been in the rubbery state.…”

Section: Incidence Of Bubble Formationmentioning

confidence: 77%

CO₂ Induced Foaming Behavior of Polystyrene near the Glass Transition

Al-Enezi

2017

International Journal of Polymer Science

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This paper examines the effect of high-pressure carbon dioxide on the foaming process in polystyrene near the glass transition temperature and the foaming was studied using cylindrical high-pressure view cell with two optical windows. This technique has potential applications in the shape foaming of polymers at lower temperatures, dye impregnation, and the foaming of polystyrene. Three sets of experiments were carried out at operating temperatures of 50, 70, and 100°C, each over a range of pressures from 24 to 120 bar. Foaming was not observed when the polymer was initially at conditions below Tg but was observed above Tg. The nucleation appeared to occur randomly leading to subsequent bubble growth from these sites, with maximum radius of 0.02–0.83 mm. Three models were applied on the foaming experimental data. Variable diffusivity and viscosity model (Model C) was applied to assess the experimental data with the WLF equation. The model shows very good agreement by using realistic parameter values. The expansion occurs by diffusion of a dissolved gas from the supersaturated polymer envelope into the bubble.

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“…[ 19 ] From these works it seems that the depression in the T g of different polymers is more pronounced at high pressures (up to 124 bar) at temperatures near or above the atmospheric pressure T g value (in the absence of CO 2 ): 120–160 °C for polycarbonate, 60–100 °C for polystyrene and 80–100 °C for PMMA. [ 17 ] Specific interactions have also been reported for oxygen donors of carbonyl groups (CO) contained in PMMA and PVAC. [ 20–22 ] In the present work, the obtained copolymers are, in general, rich in GMA with molar fractions of the olefin equal to or below 0.25.…”

Section: Resultsmentioning

confidence: 99%

“…In this case, CO 2 behaves as a plasticizer giving rise to a reduction of the glass transition temperature (T g ) which essentially means a reduction in the viscosity of the molten polymer, which is particularly interesting for polymer processing. [16][17][18][19] In this sense, some studies suggested that CO 2 forms electron-donor-acceptor complexes with electron-donating functional groups of certain polymers, such as polymethyl methacrylate (PMMA) and poly(vinyl acetate) (PVAC). [20][21][22] On the other hand, in a recent publication, our group reported the free radical copolymerization of 1-octene (Oct) and glycidyl methacrylate (GMA) and the use of the copolymer as a copper nanoparticle stabilizer in organic solvents.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the Precipitation Copolymerization of 1‐Octene and Glycidyl Methacrylate in Supercritical Carbon Dioxide

Rosales‐Guzmán

Herrera‐Morales

Mendoza‐Carrizales

et al. 2022

Macro Reaction Engineering

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The free radical precipitation copolymerization of the polar monomer glycidyl methacrylate (GMA) and the nonpolar monomer 1‐octene (Oct) in supercritical carbon dioxide (sc‐CO2) is reported under different conditions of pressure and temperature. According to 1H NMR studies, in the obtained statistical copolymers (GMA‐stat‐Oct) the molar fraction of the olefin (FOct) increases when the pressure and temperature of the reaction increased from the reference values T = 125 °C and P = 34 bar. In particular, when the initial molar fraction of Oct (fOct) is 0.83, the molar fraction of this monomer in the final copolymer reaches a maximum value of 0.22 at 124 bar and T = 155 °C. On the other hand, for fOct = 0.89, it is obtained that FOct = 0.25 at 124 bar and T = 155 °C. Copolymers obtained are characterized by NMR, scanning electron microscopy, and size exclusion chromatography techniques. Finally, two copolymers were selected to demonstrate the feasibility of modifying the GMA moiety in order to introduce OH polar groups giving rise to Oct‐stat‐glycerol methacrylate copolymers.

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Mechanical Measurement of the Plasticization of Polymers by High-Pressure Carbon Dioxide

Cited by 8 publications

References 24 publications

110th Anniversary: Gas and Vapor Sorption in Glassy Polymeric Membranes—Critical Review of Different Physical and Mathematical Models

110th Anniversary: Gas and Vapor Sorption in Glassy Polymeric Membranes—Critical Review of Different Physical and Mathematical Models

CO₂ Induced Foaming Behavior of Polystyrene near the Glass Transition

On the Precipitation Copolymerization of 1‐Octene and Glycidyl Methacrylate in Supercritical Carbon Dioxide

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Mechanical Measurement of the Plasticization of Polymers by High-Pressure Carbon Dioxide

Cited by 8 publications

References 24 publications

110th Anniversary: Gas and Vapor Sorption in Glassy Polymeric Membranes—Critical Review of Different Physical and Mathematical Models

110th Anniversary: Gas and Vapor Sorption in Glassy Polymeric Membranes—Critical Review of Different Physical and Mathematical Models

CO2 Induced Foaming Behavior of Polystyrene near the Glass Transition

On the Precipitation Copolymerization of 1‐Octene and Glycidyl Methacrylate in Supercritical Carbon Dioxide

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Product

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CO₂ Induced Foaming Behavior of Polystyrene near the Glass Transition