Drying of a Multicomponent Polymeric Coating Film: Modelling and Experiments (original) (raw)
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Drying of binary thin film polymeric coatings: an experimental study
Polish Journal of Chemical Technology, 2012
Four binary polymer -solvent systems, poly(styrene)-tetrahydrofuran, poly(styrene) - p-xylene, poly(methyl methacrylate) - ethylbenzene and poly(methyl methacrylate) - tetrahydrofuran, systems have been studied. It has been observed that thicker coatings will retain a higher amount of the residual solvent as compared to thinner coatings. In the case of poly(styrene)-tetrahydrofuran coating residual solvent remaining within the coatings were 9.09% and 4.74% for the coatings of the thicknesses of 967 micron and 559 micron, respectively. Similar trends were also observed in the case of poly(methyl methacrylate)-ethylbenzene, poly(methyl methacrylate)-tetrahydrofuran, and poly(styrene)-p-xylene systems.
Modeling of multicomponent drying of polymer films
AIChE Journal, 1999
The drying of ®olatile sol®ents from a coated film is a complicated process since it in®ol®es simultaneous heat and mass transfer controlled by complex transport and thermodynamic beha®ior of polymer solutions. In this work, a model is de®eloped to describe the drying beha®ior of multicomponent polymer solutions deposited on the impermeable substrate. A key component of the model is incorporation of multicomponent diffusion coefficients that consist of thermodynamic factors and self-diffusi®ities. Vrentas-Duda free-®olume theory was used for predicting concentration and temperature dependency of self-diffusion coefficients. Drying processes in o®ens with different zones in which temperature, ®elocity, andror partial pressure of each sol®ent ®ary from zone to zone are considered. The predictions from the models pro®ide detailed information about the relati®e importance of internal and external resistances to drying, effect of operating conditions, effect of the multiple-zone approach, as well as sensiti®ity of all physical properties on the drying rate. The ®alidity of the model was confirmed by comparing predictions with the drying data a®ailable in the literature and the data collected in our laboratories. The experimental data and the simulation results are in good agreement.
Drying of Multilayer Polymeric Coatings, Part I: An Experimental Study
Drying Technology, 2014
Designing of multilayer coatings of poly(styrene)-tetrahydrofuran and poly(methyl methacrylate)-tetrahydrofuran has been studied. Multilayers were prepared by layer-by-layer and simultaneous methods. Several binary polymeric coatings of poly(styrene)tetrahydrofuran and poly(methyl methacrylate)-tetrahydrofuran systems have been dried under quiescent drying conditions. Gravimetric analyses were performed using an analytical weighing balance. The initial amount of polymer was kept constant in both solution coatings. Coating which is likely to go through the glass transition temperature should be applied on the bottom side in order to minimize the residual solvent. For instance, residual solvent content is high in multilayer coating having poly(methyl methacrylate)-tetrahydrofuran coating on the top and poly (styrene)-tetrahydrofuran coating on the bottom, as compared to multilayer coatings having poly(styrene)-tetrahydrofuran on the top of poly(methyl methacrylate)-tetrahydrofuran coating.
Several binary polymeric coatings of poly(styrene) -tetrahydrofuran have been dried under quiescent drying conditions. Coatings are made using four different solutions of polymer having 5. 0104, 9.75, 10.06, and 15.14 % wt poly(styrene) initially. Experiments were performed for several different thicknesses for each polymer solution. Residual solvent remaining is lowest in the thicker coating. Results show that the thicker coating should be applied once rather than layer by layer to minimize the residual solvent remaining. Next layer is applied after the complete drying of previous layer. This practice should continue till we get desired thickness. For an instance, coating of initial thickness: 1010 m µ and final thickness: 61 m µ have residual solvent: which is lower than the residual solvent in dried coatings of nearly same final thicknesses using layer by layer technique.
Experimental Investigation of Industrial Coating-Drying Process Parameters
Drying Technology, 2011
Effects on air impingement convective drying of coated paper from variation in coating composition, coating-to-drying delay time, and drying intensity were investigated using six combinations of these three independently controlled process parameters for a fixed coat weight of 10.2 ± 0.5 g/m on commercial 37.7 g/m LWC base paper. The reliability of these experimental results was established through critical tests employing 8 or 10
Non-Fickian Drying of Polymeric Coatings
ijstr.org
Abstract-Concentration profiles in two binary polymeric coatings-poly (styrene)‒p-xylene and poly (methyl methacrylate)‒ethylbenzene, have been measured using confocal laser Raman spectroscopy. Measured profiles are very different from as shown earlier for ...
2012 IJSTR 1 1 1 6 Non-Fickian Drying of Polymeric Coatings
Concentration profiles in two binary polymeric coatings -poly (styrene) -p-xylene and poly (methyl methacrylate)ethylbenzene, have been measured using confocal laser Raman spectroscopy. Measured profiles are very different from as shown earlier for rubbery coatings. Sigmoidal profiles are observed in these polymeric coatings during the course of drying because they went through the glass transition temperature. Fick's law of diffusion is inadequate to explain such type of diffusion.
Polymer, 2004
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
An Analytical Solution of the Convective Drying of a Multicomponent Liquid Film
Analytical solutions of the diffusion and conduction equations applied to liquid-side-controlled convective drying of a multicomponent liquid film are developed. Assuming constant physical properties of the liquid, the equations describing interactive mass transfer are decoupled by a similarity transformation and solved simultaneously with conduction equation by the method of variable separation. Variations of physical properties along the process trajectory are taken into account by a stepwise application of the solution in time intervals with averaged coefficients from previous time steps. Despite simplifications, the analytical solution gives a good insight into the selectivity of the drying process and is computationally fast.