Supercritical devolatilization of polymers

Alsoy, Sacide

doi:10.1002/aic.690440309

Cited by 37 publications

(35 citation statements)

References 27 publications

(33 reference statements)

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“…Monomer transport rates (in terms of D mon P ) in the polymer phase swollen with CO 2 increase from values 10 to about 10 or even higher (Alsoy and Duda, 1998), leading to improved monomer transport rates compared to e.g. steam stripping.…”

Section: Pressurized Carbon Dioxide As Alternative Methods To Reduce Rmentioning

confidence: 99%

“…Based on the aspect ratio in Figure 9b, (sc)CO 2 flow rate of 3050 kg/hr, has been chosen as a base case in this work. Tables 1 and 2 to 10 < D < 10 due to the plasticizing effect of CO 2 (Alsoy, 1998). To analyze the effect of the transport constant of styrene in the polymer phase, the CO 2 residence time has been calculated for D 10 and for D 10 .…”

Section: Dispersed Phase Hold Upmentioning

confidence: 99%

“…Solubility and diffusivity of the monomer in (sc)CO 2 can easily be tuned by (small) changes in pressure and temperature. Due to the plasticizing effect the diffusion coefficient (D m P ) of the monomer in the polymer particles increases from 10 to 10 or even higher (Alsoy and Duda, 1998).…”

Section: Introductionmentioning

confidence: 99%

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Residual Monomer Reduction in Polymer Latex Products by Extraction with Supercritical Carbon Dioxide

Aerts

Meuldijk

Kemmere

et al. 2011

Macromolecular Symposia

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Summary: Extraction of residual monomer from a latex product with supercritical carbon dioxide ((sc)CO2) in a column was studied. Operating conditions were chosen at 35 °C and 100 bar. For reducing the residual styrene level in a polystyrene latex from 104 ppm to 100 ppm and from 104 ppm to 10 ppm, a countercurrent bubble column with latex as continuous and (sc)CO2 as dispersed phase is suggested. Monomer partitioning was demonstrated to be a key parameter in the equipment design. Monomer transport was found to be governed by the shuttle effect, caused by Brownian motion of the latex to and from the H2O/CO2 interface. The drift‐flux approach was followed to determine the column flooding conditions. Small column volumes are obtained. (sc)CO2 is a promising extraction medium for residual monomer reduction in latex products. Performance towards steam stripping is better as the final residual monomer level becomes lower.

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Section: Pressurized Carbon Dioxide As Alternative Methods To Reduce Rmentioning

confidence: 99%

Section: Dispersed Phase Hold Upmentioning

confidence: 99%

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Residual Monomer Reduction in Polymer Latex Products by Extraction with Supercritical Carbon Dioxide

Aerts

Meuldijk

Kemmere

et al. 2011

Macromolecular Symposia

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“…[8][9][10] Numerous mathematical models have been developed by various researchers to study the drying behavior of amorphous and semicrystalline polymers. [15][16][17][18][19][20][21][22][23][24][25][26] Our previous studies of the drying behavior of multicomponent semicrystalline polymers lead to the development of a new crystallization kinetics model for polymers undergoing drying processes. 27,28 This model utilizes the Vrentas-Duda free volume theory to determine the mobility of the amorphous phase in the presence of solvents and their capability to form crystals.…”

Section: Introductionmentioning

confidence: 99%

Crystallization of poly(vinyl alcohol) during solvent removal: Infrared characterization and mathematical modeling

Wong

Altınkaya

Mallapragada

2007

J Polym Sci B Polym Phys

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Crystallization of semicrystalline polymer films during drying has a significant effect on the rate of solvent removal. Understanding and controlling the crystallization kinetics is important in controlling residual solvent levels and drying kinetics. The degree of crystallinity of the poly(vinyl alcohol) films during multicomponent drying was investigated using Fourier transform infrared spectroscopy (FTIR). The 1141 cm À1 band is sensitive to the degree of crystallinity of the polymer and the growth of intensity of this band was monitored as drying progressed. The results from the FTIR studies were comparable to the results obtained from differential scanning calorimetry. Studies were conducted to test the effect of initial solvent composition (water-methanol mixture), drying temperature, and polymer molecular weight on the rate of crystallization and the final crystallinity of the films. An increase in initial methanol composition increased the crystallization rate but did not affect the final degree of crystallinity. An increase in drying temperature and decrease in polymer molecular weight increased the rate of crystallization as well as the final degree of crystallinity. Based on the experimental data, rate constants for crystallization kinetics were extracted from our previously developed model based on free volume theory. The experimental data and the simulation results showed good agreement. The ability of the free volume theory to illustrate the crystallization behavior validated the model and improved its capability.

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“…1,2 The microstructure of the polymer changes constantly during drying as the solvent is removed and the polymer chains realign themselves. 3 In the design of drying processes, several issues need to be addressed, including the viscoelasticity of the polymer, the final solvent residual content in the film, and the structural integrity of the film.…”

Section: Introductionmentioning

confidence: 99%

Understanding the effect of skin formation on the removal of solvents from semicrystalline polymers

Wong

Altınkaya

Mallapragada

2005

J Polym Sci B Polym Phys

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The effect of glassy skin formation on the drying of semicrystalline polymers was investigated with a comprehensive mathematical model developed for multicomponent systems. Polymers with high glass-transition temperatures can become rubbery at room temperature under the influence of solvents. As the solvents are removed from the polymer, a glassy skin can form and continue to develop. The model takes into account the effects of diffusion-induced polymer crystallization as well as glassy-rubbery transitions on the overall solvent content and polymer crystallinity. A Vrentas-Duda free-volume-based diffusion scheme and crystallization kinetics were used in our model. The polymer-solvent system chosen was a poly(vinyl alcohol) (PVA)-water-methanol system. The drying kinetics of PVA films were obtained by gravimetric methods with swollen films with known water/methanol concentrations. The overall drying behaviors of the polymer system determined by our model and experimental methods were compared and found to match well.

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Supercritical devolatilization of polymers

Cited by 37 publications

References 27 publications

Residual Monomer Reduction in Polymer Latex Products by Extraction with Supercritical Carbon Dioxide

Residual Monomer Reduction in Polymer Latex Products by Extraction with Supercritical Carbon Dioxide

Crystallization of poly(vinyl alcohol) during solvent removal: Infrared characterization and mathematical modeling

Understanding the effect of skin formation on the removal of solvents from semicrystalline polymers

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