Diffusion Coefficients in Polymer-Solvent Systems for Highly Concentrated Polymer Solutions

Abstract

The Vrentas/Duda proposal for the diffusion of polymer-solvent systems, which is based on the free-volume theory, was employed in correlating and predicting mutual diffusion coefficients in highly concentrated polymer solutions. It has been observed that the predictive version of the model is capable of qualitatively representing the experimental data, while the use of an adjustable parameter greatly improves the performance of the model. The systems studied were poly(vinyl) acetate-toluene and Neoprene-acetone, and a comparison between experimental data and calculated values from the Vrentas/Duda model is reported. A new experimental apparatus based on the sorption technique was built to provide reliable diffusivity data on the Neoprene-acetone system

Co-Bonded Hybrid Thermoplastic-Thermoset Composite Interphase: Process-Microstructure-Property Correlation

“…It can be seen in Figure 10 a that the fitted diffusivity was found to be in the range of 10 −12 –10 −10 (m 2 /s) for the temperature range of 25–60 °C. The estimated magnitudes of the diffusivities matched with the reported diffusivities of other systems such as epoxy-PSU [ 26 , 52 ], amine-PSU [ 26 , 52 ], toluene-PEEK (for 0% initial crystallinity of PEEK) [ 53 ], CS2-PEEK (for 0% initial crystallinity of PEEK) [ 53 ] and toluene-PVAc (for mass fraction of toluene of 0.1) [ 54 ] as seen in Figure 10 a. The trend of the temperature dependent diffusivity was captured well with the temperature dependent model given in Equation (5) with m 2 /s and cal/mol.…”

Effect of network connectivity on the mechanical and transport properties of block copolymer gels

“…Unlike mechanical behavior, we hypothesize nanocarrier diffusion in DDOGs should remain largely unchanged within each fixed-w p series because total copolymer concentration, not network connectivity, is expected to impact mass transport. 29,30,41 Nanocarrier release experiments were conducted following a previously published FTIR-based protocol in order to evaluate this hypothesis. 28 The evolution of gel FTIR profiles over time (Figures S10, S11, S12) enables determination of nanocarrier retained mass (m/m 0 ) profiles for each formulation of interest.…”

“…27,28 The rate of solute transport within gels, on the other hand, generally decreases with increasing polymer concentration because polymer chains serve as barriers to diffusion. 29,30 Clearly, mechanical behavior and nanocarrier mobility are inexorably linked through copolymer concentration. We hypothesize that modulating DDOGs network connectivity independent of total copolymer concentration will allow for decoupling of mechanical and transport properties.…”

Experimental determination of possible diffusion models during pervaporation process in polymer membranes

“…Данная теория была модифицирована [13,14] для возможности предсказа ния диффузии с помощью параметров свободного объема полимера и пене транта. Важная особенность этой модификации состоит в допущении проведе ния для молекулы пенетранта диффузионного прыжка, в который вовлечена только часть молекулы.…”