Understanding isothermal semicrystalline polymer drying: Mathematical models and experimental characterization

Ngui, Meo O.; Mallapragada, Surya K.

doi:10.1002/(sici)1099-0488(19981115)36:15<2771::aid-polb11>3.0.co;2-1

Cited by 44 publications

(33 citation statements)

References 15 publications

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“…Several mathematical models for describing the drying behavior of amorphous polymers have been proposed by various researchers [1,2,19 -22], but there have been few studies of multicomponent semicrystalline polymer drying [24,25]. A schematic setup of the drying process is shown in Fig.…”

Section: Mathematical Modelingmentioning

confidence: 99%

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Drying of semicrystalline polymers: mathematical modeling and experimental characterization of poly(vinyl alcohol) films

Wong

Altınkaya

Mallapragada

2004

Polymer

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A mathematical model was developed to predict the drying mechanism of semicrystalline polymers involving multiple solvents. Since drying of semicrystalline polymers can be accompanied by changes in polymer degree of crystallinity, the model integrates crystallization kinetics and the Vrentas -Duda diffusion model to provide a better understanding of the mechanism. The model considers the effect of external conditions such as temperature, film shrinkage and diffusion and evaporation of multiple solvents during drying. Poly(vinyl alcohol) (PVA)/water/methanol was chosen as a test system. The drying kinetics of PVA films swollen in water and methanol were investigated using gravimetric techniques. The model predicts that higher temperatures, lower film thicknesses and lower methanol to water ratios increase the drying rate. The model predictions were compared with experimental data and showed good agreement. q

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Section: Mathematical Modelingmentioning

confidence: 99%

“…Ngui and Mallapragada [24,25] used a firstorder kinetic expression to predict the crystallinity growth for a single solvent system, and this expression is extended to multiple solvent systems as shown in Eq. (14).…”

Section: Mathematical Modelingmentioning

confidence: 99%

Drying of semicrystalline polymers: mathematical modeling and experimental characterization of poly(vinyl alcohol) films

Wong

Altınkaya

Mallapragada

2004

Polymer

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“…This is physically reasonable, because here the leading order is O( −1/2 ). Since the skin is known to slow desorption [16,17], it is clear that the flux through the skin should be no larger than O(1). The last condition needed for our layer problem is a matching condition; we note from (3.3) that the appropriate one for our problem is…”

Section: Boundary Layermentioning

confidence: 99%

“…This glassy skin can be exploited for the production of more effective protective clothing, equipment, or sealants from polymer materials [13,Chapter 17], [14, Chapter 1, Section 4.9], [15]. On the other hand, polymer skinning is undesirable in coating processes due to a decrease in the drying rates and the formation of nonuniformities in the polymer coating [5,16].…”

Section: Introductionmentioning

confidence: 99%

A Spatially Nonlocal Model for Polymer Desorption

Edwards

2005

J Eng Math

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Abstract. In order to describe diffusion of a penetrant in a polymer entanglement network, one must incorporate nonlocal effects. Most previous models have included nonlocality in time only; however, by exploiting the disparate length scales in such systems, one can model these effects by a partial integrodifferential equation which is nonlocal in space. When considering the case of diffusion near the glass-rubber transition, a moving boundary separates the polymer into two regions, each governed by a different set of PDEs. The desorption of a semi-infinite polymer is studied using singular perturbation methods. Layers arise at the exposed surface, at the moving boundary, and initially. Analytical and phase-plane solutions are obtained for the solution, which exhibits physically realistic forms of desorption overshoot. Thus, spatially nonlocal models have the potential to replicate experimental systems, and should be considered in concert with other viscoelastic models of polymer-penetrant systems.

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“…Although the drying process of semicrystalline polymer systems with single solvents has been investigated extensively, [1][2][3] the knowledge of drying processes of semicrystalline polymer systems involving multiple solvents is still scarce. As the polymer films undergo a drying process, their structure and properties change, and careful monitoring is needed to ensure that the quality of the product meets the required specification.…”

Section: Introductionmentioning

confidence: 99%

Multi-Zone Drying Schemes for Lowering the Residual Solvent Content during Multi-Component Drying of Semicrystalline Polymers

2007

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The development of a glassy skin in multicomponent semicrystalline polymer systems limits the diffusion of solvents out of the system and increases residual solvent levels. Based on the results of a mathematical model that we had previously developed, we have proposed a multi-zone drying scheme aimed at lowering the residual solvent levels by taking into account the effect of interactions between the various solvents as predicted by the model. This article focuses on the application of this model to develop optimal drying schemes and to verify the effectiveness of these predictions using experimental techniques. The mathematical model developed previously to study the diffusion of multiple solvents and changes in the crystallinity of semicrystalline polymer systems during drying incorporates many features including Vrentas-Duda diffusion theory, solvent-induced crystallization kinetics, as well as glass transition effects and skinning of the film. The multi-zone drying system was developed by varying the drying temperature in each zone as well as changing the partial pressure of individual solvents during the drying process. The effectiveness of the multizone drying schemes predicted by the model was validated experimentally using thermogravimetric methods. The polymer-solvent system chosen was a poly(vinyl alcohol)-water-methanol system. Our experimental data suggested that the multi-zone drying schemes were superior to a single-zone drying system through direct comparison. Further examination of the mathematical model yielded individual solvent profiles and these data reaffirmed our conclusions that a multi-zone drying scheme has the ability to reduce the effect of solvent trapping and thus lower the overall residual solvent content.

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Understanding isothermal semicrystalline polymer drying: Mathematical models and experimental characterization

Cited by 44 publications

References 15 publications

Drying of semicrystalline polymers: mathematical modeling and experimental characterization of poly(vinyl alcohol) films

Drying of semicrystalline polymers: mathematical modeling and experimental characterization of poly(vinyl alcohol) films

A Spatially Nonlocal Model for Polymer Desorption

Multi-Zone Drying Schemes for Lowering the Residual Solvent Content during Multi-Component Drying of Semicrystalline Polymers

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