Analysis of nonsolvent–solvent–polymer phase diagrams and their relevance to membrane formation modeling

Yılmaz, Levent; McHugh, A. J.

doi:10.1002/app.1986.070310404

Cited by 232 publications

(170 citation statements)

References 27 publications

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“…The PIBtoluene activity data (previously published in the literature) was measured at 25°C [25]. The group contribution activity coefficient method developed by Chen et al [28] showed that the difference between the PIB-toluene activity coefficient at 25°C and at 23°C was less than 0.2%.…”

Section: Methodsmentioning

confidence: 99%

“…6, the vapor pressure of the analyte can be related to the volume fraction of the analyte in the composite and the interaction parameter by (9) Similar thermodynamic equations for systems with more than two components can be derived based on Flory theory [20]. For example, the equation of the analyte1/analyte2/ polymer ternary system has been derived and widely used [20,[23][24][25]]. …”

Section: Thermodynamic Modelmentioning

confidence: 99%

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Modeling carbon black/polymer composite sensors

Hua

Pitt

McGrath

et al. 2007

Sensors and Actuators B: Chemical

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Conductive polymer composite sensors have shown great potential in identifying gaseous analytes. To more thoroughly understand the physical and chemical mechanisms of this type of sensor, a mathematical model was developed by combining two sub-models: a conductivity model and a thermodynamic model, which gives a relationship between the vapor concentration of analyte(s) and the change of the sensor signals. In this work, 64 chemiresistors representing eight different carbon concentrations (8-60 vol% carbon) were constructed by depositing thin films of a carbon-black/polyisobutylene composite onto concentric spiral platinum electrodes on a silicon chip. The responses of the sensors were measured in dry air and at various vapor pressures of toluene and trichloroethylene. Three parameters in the conductivity model were determined by fitting the experimental data. It was shown that by applying this model, the sensor responses can be adequately predicted for given vapor pressures; furthermore the analyte vapor concentrations can be estimated based on the sensor responses. This model will guide the improvement of the design and fabrication of conductive polymer composite sensors for detecting and identifying mixtures of organic vapors.

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Section: Methodsmentioning

confidence: 99%

Section: Thermodynamic Modelmentioning

confidence: 99%

Modeling carbon black/polymer composite sensors

Hua

Pitt

McGrath

et al. 2007

Sensors and Actuators B: Chemical

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“…In previous studies, the concentration dependence of the water/cellulose acetate binary interaction parameter was ignored in order to avoid the use of any adjustable parameter [4,17]. Yilmaz and McHugh [32] have shown that shapes of the binodal and spinodal curves generated from constant and concentration dependent solvent-nonsolvent interaction parameters are similar. They concluded that ternary phase diagrams can be calculated using constant solvent/nonsolvent interaction parameters within the characteristic experimental range.…”

Section: Determination Of Phase Diagrams and Composition Pathsmentioning

confidence: 99%

“…They concluded that ternary phase diagrams can be calculated using constant solvent/nonsolvent interaction parameters within the characteristic experimental range. Furthermore, Yilmaz and McHugh [32] point out the fact that data for the concentration dependence of solvent-polymer interaction parameters are quite limited and experimental difficulties limit their accuracy. Thus, empirical fits of low order (i.e., linear form) are used although they have relatively poor accuracy.…”

Section: Determination Of Phase Diagrams and Composition Pathsmentioning

confidence: 99%

Membrane formation by dry-cast process

Altınkaya

Yenal

Ozbas

2005

Journal of Membrane Science

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Asymmetric membranes were prepared by dry-cast phase inversion technique from a cellulose acetate, acetone, water solution in order to assess the validity of the mathematical model recently developed by us. Based on the model predictions, general structural characteristics of the membranes were determined by plotting the composition paths on the ternary phase diagram and polymer concentration profile at the first moment of precipitation. Composition paths on the ternary phase diagram enable the assessment of whether a phase separation occurs and allow prediction of inception time and duration of the phase separation. The polymer distribution at the moment of precipitation provides a rough thickness of the high polymer concentration region near the interface and a pore distribution of the sublayer structure. The effects of polymer/nonsolvent ratio in the casting solution, the initial film thickness, evaporation temperature, relative humidity and velocity of air were investigated. Model predictions were compared with the morphological analysis conducted using scanning electron microscopy. Results show that diffusion formulation plays an important role in capturing the accurate structure of the membrane from the model predictions.

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“…The binodal line is the boundary between the stable and the metastable region of the polymer solution, whereas the spinodal line sets the limits between the meta-stable and the unstable region in the phase diagram. The binodal and spinodal lines can be calculated using the Flory-Huggins theory (28)(29). Phase separation of an initially stable polymer solution can be the result of two mechanisms: (i) nucleation and growth or (ii) spinodal decomposition.…”

Section: Symmetric Membranesmentioning

confidence: 99%