Molecular diffusion in polymer solutions

Vrentas, J. S.; Duda, J. L.

doi:10.1002/aic.690250102

Cited by 253 publications

(143 citation statements)

References 89 publications

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“…where B 1 and B 2 are empirically determined constants, n is the number of gas molecules in a critical bubble, F * is the modified change in free energy, and D = D(T ) is the diffusivity of the volatile molecule in the polymer solution [36]. This model predicts nucleation rates on the order of J ≈ 10…”

Section: Bubble Nucleationmentioning

confidence: 99%

A numerical model for combustion of bubbling thermoplastic materials in microgravity

Butler¹

2002

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Section: Bubble Nucleationmentioning

confidence: 99%

A numerical model for combustion of bubbling thermoplastic materials in microgravity

Butler¹

2002

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“…Diffusion coefficient in polymer/solvent system over a wide range of concentrations and temperatures can be obtained by using a "free volume theory" of Vrentas and Duda (1979). In the present work, drying of acrylic acidacrylamide copolymer was carried out under various operating conditions.…”

Section: Introductionmentioning

confidence: 99%

Drying and shrinkage of polymer gels

Waje

Meshram

Chaudhary

et al. 2005

Braz. J. Chem. Eng.

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-The polymer hydrogel was synthesized by photo-polymerization process (UV light, 60 O C) in presence of Photo-initiator (Irgacure R ) and Cross-linker (NN'-methylene bisacrylamide; MBAM). In the present work, the drying of polymer hydrogel was carried out to study the effect of temperature, gel-sheet thickness, monomer ratio of acryl acid to acrylamide (AA/AM), concentration of MBAM and quantity of monomers. A correlation has been developed for modified sheet thickness as a function of contraction coefficient and degree of drying. Effective diffusivity was estimated from Fickian-diffusive model considering modified sheet thickness and was found to be in the range of 1.1 × 10 -10 -5.93 × 10 -10 m 2 /s. The activation energy obtained using Arrhenius type equation was found to be in the range of 2979-10737 kJ/kmol H 2 O. The drying behavior shows an initial shoot-up in drying rate followed by constant rate and two falling rate periods.

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“…Values of D 2,eq and β 2 were obtained by fitting the experimental data of caffeine release from the caffeine-loaded hydrogels. With Fujita-type diffusion, the diffusion coefficient of a particle is related to the volumetric and free-volume properties of all components (Vrentas and Duda 1977). With the system considered ideal, the total volume of the matrix at any time is calculated by summing the biopolymer, the bioactive compound, and water volumes.…”

Section: Mathematical Modelmentioning

confidence: 99%

Modeling of Caffeine Release from Crosslinked Water-Swellable Gelatin and Gelatin-Maltodextrin Hydrogels

Abbasi¹,

Eslamian

Rousseau

2008

Drug Delivery

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Research from this group has recently led to the development of a genipin-crosslinked gelatin gel that may be used as a controlled release matrix for bioactive compounds. This study presents a model that simulates the release of entrapped caffeine from the hydrogel and the ingress of water into these gels. Fick's second law Abbreviations: A, Dimensionless front-fixing radius; B, Dimensionless front-fixing height; C 0 , Caffeine concentration at initial conditions in the cylindrical matrix; C 1,eq , Equilibrium water concentration in the fully swollen cylindrical matrix; C 1 , Water concentration in the cylindrical matrix; C 2 , Caffeine concentration in the cylindrical matrix;C 1 , Dimensionless water concentration in the cylindrical matrix; C 2 , Dimensionless caffeine concentration in the cylindrical matrix; D 1 , Water diffusion coefficient in the cylindrical matrix; D 2 , Caffeine diffusion coefficient in the cylindrical matrix; D 1,eq , Diffusion coefficient of caffeine in the fully swollen cylindrical matrix; D 2,eq , Diffusion coefficient of water in the fully swollen cylindrical matrix; r , Radial coordinate in the cylindrical matrix; r 0 , Initial radius of the cylindrical matrix;r , Dimensionless radius of the cylindrical matrix; r N , New radius of the cylindrical matrix; r t , (New radius of the cylindrical matrix)/(initial radius of the cylindrical matrix); t, Time; z, Axial coordinate in the cylindrical matrix; z 0 , Initial half-height of the cylindrical matrix;z, Dimensionless half-height of the cylindrical matrix; z N , New half height of cylindrical matrix; z t , (New half-height of the cylindrical matrix)/(initial half-height of the cylindrical matrix); V p , Dry matrix volume; β 1 , Dimensionless constant for the diffusion of water; β 2 , Dimensionless constant for the diffusion of caffeine; ρ 1 , Density of water; ρ 2 , Density of caffeine; τ , Dimensionless time.of diffusion is used to describe the water penetration and bioactive release in the system. To validate the model, caffeine release experiments from the gel were carried out. The predicted bioactive release profiles are in very good agreement with experimental data at different gel compositions. The model may also be used for a wide range of bioactive molecules and hydrogels with different cylindrical dimensions.

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Molecular diffusion in polymer solutions

Cited by 253 publications

References 89 publications

A numerical model for combustion of bubbling thermoplastic materials in microgravity

A numerical model for combustion of bubbling thermoplastic materials in microgravity

Drying and shrinkage of polymer gels

Modeling of Caffeine Release from Crosslinked Water-Swellable Gelatin and Gelatin-Maltodextrin Hydrogels

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