Inverse gas chromatography measurements

VE Ovejero, G., Perez, P., Romero, M.D., Diaz, I., and Diez, E., SEES triblock copolymer-solvent interaction parameters from inverse gas chromatography measurements, Eur. Polym. J., 45, 590, 2009. 

Most of the entries in the table below were obtained from osmotic pressure, vapor sorption, or inverse gas chromatography measurements [5]. 

MOR Morales, E. and Acosta, J.L., Polymer solubility parameters of poly(propylene oxide) rubber from inverse gas chromatography measurements, Polym. J., 28,127,1996. 

AI-Ghamdi, A. and Al-Saigh, Z.Y. (2000) SEES triblock copolymer-solvent interaction parameters from inverse gas chromatography measurement f Pdym. Sci., Part B Polym. Phys., 38,1155-1166. 

Finally, note that some phenomena typical of real systems were neglected in the previous text. Such effects are, for instance, the distribution of activity of adsorption sites on filler surface as has been obtained from the inverse gas chromatography measurements [35] or highei- equilibiimn concentration of longer chains at the interface compared to the bulk [36]. However, they seem to be of second order effects according to experimental data reported. 

Several properties of the filler are important to the compounder (279). Properties that are frequentiy reported by fumed sihca manufacturers include the acidity of the filler, nitrogen adsorption, oil absorption, and particle size distribution (280,281). The adsorption techniques provide a measure of the surface area of the filler, whereas oil absorption is an indication of the stmcture of the filler (282). Measurement of the sdanol concentration is critical, and some techniques that are commonly used in the industry to estimate this parameter are the methyl red absorption and methanol wettabihty (273,274,277) tests. Other techniques include various spectroscopies, such as diffuse reflectance infrared spectroscopy (drift), inverse gas chromatography (igc), photoacoustic ir, nmr, Raman, and surface forces apparatus (277,283—290). 

One may also be able to determine the work of adhesion for cases in which the contact angle is zero by using probe liquids, as described later in this chapter. There are also other ways of determining the work of adhesion, such as inverse gas chromatography, which do not depend solely on capillary measurements (surface tension and contact angle). This too will be discussed later. 

Fig. 17. A schematic of the alkane line obtained by inverse gas chromatography (IGC) measurements. The relative retention volume of carrier gas required to elute a series of alkane probe gases is plotted against the molar area of the probe times the. square root of its surface tension. The slope of the plot is yielding the dispersion component of the surface energy of...

The adsorption of gas onto a solid surface can also be used to estimate surface energy. Both inverse gas chromatography (IGC) and isotherm measurement using the BET method [19] have been used. Further discussion and detailed references are given by Lucic et al. [20] who compare the application of IGC, BET and contact angle methods for characterising the surface energies of stearate-coated calcium carbonate fillers. 

This expression can be modified to apply directly to any of various techniques used to measure the interaction parameter, including membrane and vapor osmometry, freezing point depression, light scattering, viscometry, and inverse gas chromatography [89], A polynomial curve fit is typically used for the concentration dependence of %, while the temperature dependence can usually be fit over a limited temperature range to the form [47]... 

Once the durability testing of the fuel cells is finalized, the internal components are then characterized. For diffusion layers, some of these characterization techniques include SEM to visualize surface changes, porosimetry measurements to analyze any changes in porosity within the DL and MPL, IGC (inverse gas chromatography) to identify relative humidity effects on the hydrophobic properties of the DLs, contact angle measurements to observe any changes in the hydrophobic/hydrophilic coatings of the DL, etc. [254,255]. 

Contact angle measurements Isothermal microcalorimetry Gravimetric sorption Inverse gas chromatography Differential scanning calorimetry Thermogravimetric analysis Isothermal microcalorimetry Infra red analysis X-ray diffraction... 

Its related value was originally denoted as X- Numerous % values in terms of volume fractions are collected in Ref. [37]. Unfortunately the scatter in % values found in the literature is large as they reflect also both the polymer source (e.g., narrow molar mass fractions or anionically prepared samples) and the method of measurement, for example, light scattering, osmometry, or inverse gas chromatography. The interaction parameters g (%) for the polymer-good solvent systems assume values between 0 and 0.5 [37]. 

Lately the most frequently used technique for the determination of thermodynamic and acid/base characteristics is inverse gas chromatography [30,73-75]. In IGC the unknown filler or fiber surface is characterized by compounds, usually solvents, of known properties. IGC measurements can be carried out in two different ways. In the most often applied linear, or ideal, IGC infinite concentrations of n-alkane are injected into the column containing the filler to be characterized. The net retention volume (V ) can be calculated by ... 

Vapour and gas sorption measurements can be performed with static or dynamic methods, either of which can provide information on equilibrium behaviour. Furthermore, the measurements can be performed using gravimetric or volumetric based instrumentation. The most common flow methods are inverse gas chromatography (IGC) [1] for volumetric studies and dynamic gravimetric instrumentation [2]. 

From adsorption studies with the help of inverse gas chromatography The interaction between a stationary phase and a well known gas or solvent is measured as in standard gas chromatography. The results are, however, used to characterize the stationary phase. Therefore, let us assume that n moles adsorb on a surface A. The interface excess concentration is T = n/A. With the Gibbs equation for a two-component system (Eq. 3.55) T = — l/RT dy/d wP) we get... 

Inverse gas chromatography (IGC) is another technique that can be used to measure the specific surface area of a particulate material, as well as to measure a number of surface thermodynamic properties of powders. Such instrumentation operates on a different principle than traditional nitrogen/krypton adsorption using the BET isotherm. 

Dove JW, Buckton G, Doherty C. 1996. A comparison of two contact angle measurement methods and inverse gas chromatography to asses the surface energies of theophylline and caffeine. Int. J. Pharm. 138. 

In the case of polystyrene blends with poly(vinyl methyl ether) two phase behaviour was found for blends from various chlorinated solvents whereas single phase behaviour was found for blends from toluene The phase separation of mixtures of these polymers in various solvents has been studied and the interaction parameters of the two polymers with the solvents measured by inverse gas chromatography It was found that those solvents which induced phase separation were those for which a large difference existed between the two separate polymer-solvent interaction parameters. This has been called the A% effect (where A% = X 2 Xi 3)-A two phase region exists within the polymer/polymer/solvent three component phase diagram as shown in Fig. 2. When a dilute solution at composition A is evaporated, phase separation takes place at B and when the system leaves the two phase region, at overall... 

There are several different ways of obtaining an estimate of the interaction between two polymers. These include heat of mixing measurements, inverse gas chromatography, solvent vapour absorption, various scattering techniques and viscosity... 

Water adsorption studies are obviously indicated for the evaluation of the hydrophilic character of silica. Besides, according to our earlier studies, methylene chloride (CH2CI2), used as a probe for Inverse Gas Chromatography (IGC) measurements at Unite concentration conditions, appears to be an alternative choice for determining the hydrophobicity of silica surfaces. Indeed, earlier indications suggest that this probe, when used under appropriate conditions, is not interacting with the hydrophilic silanol groups. The present work is complementary to the study of water adsorption on fumed silica samples, described in this book [1]. 

Katsanos, N.A. Gavril, D. Kapolos, J. Karaiskakis, G. Surface energy of solid catalysts measured by inverse gas chromatography. J. Colloid Interface Sci. 2003, 270 (2), 455-461. 

Inverse Gas Chromatography (IGC) has been used to measure solubility parameters for three polymers at 25° C using the method of Guillet and DiPaola-Baranyi. The linear relationship noted with other polymers was found and the results add further credance to the method. Solubility parameters have also been calculated for six small molecule involatile compounds of the type use as plasticizers. The original method did not yield values in good agreement with literature results but estimation of the different contributions to the solution interactions allowed calculation of more meaningful values. 

Most of the available data on diffusion and diffusion coefficients of volatile liquids or gases in polymers have been obtained by static sorption experiments (10, 11), which are time consuming and require extensive data analysis. In recent years, inverse gas chromatography, IGC, was found to have wide utility in measuring sorption tendency and diffusion coefficients of gases and volatile liquids in molten polymers (12-17). 

Diffusivity data are available only for a limited number of polymer-solvent systems. This paper describes research that has led to the development of the use of capillary column inverse gas chromatography (IGC) for the measurement of diffusion coefficients of solute molecules in polymers at infinite dilution. The work has resulted in a precise, rapid technique for the diffusion measurements that circumvents the many problems attendant to classical sorption methods and packed column IGC methods. Initial results of the program appeared in two recent publications (1,2)- Some of the material introduced in those papers is discussed here to present background for... 

Inverse Gas Chromatography. A technique that promises to circumvent many of the problems attendant to gravimetric sorption experiments is Inverse Gas Chromatography (IGO. Until recently, all reported applications of IGC to the measurement of diffusion coefficients have used packed chromatographic columns in which the stationary phase is supported on a granular substrate. Equations similar to those developed by van Deemter et al. (22) are used to calculate the stationary phase diffusion coefficient from the spreading of the elution profile. The equation developed by van Deemter is commonly written as... 

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