Critical Assessment of Inverse Gas Chromatography as Means of Assessing Surface Free Energy and Acid–Base Interaction of Pharmaceutical Powders

2007 ◽  
Vol 96 (10) ◽  
pp. 2647-2654 ◽  
Author(s):  
Martin J. Telko ◽  
Anthony J. Hickey
Keyword(s):  
Gas Chromatography ◽  
Free Energy ◽  
Surface Free Energy ◽  
Inverse Gas Chromatography ◽  
Critical Assessment ◽  
Pharmaceutical Powders ◽  
Acid Base ◽  
Base Interaction ◽  
Acid Base Interaction

Surface characterization of carbon fibers by inverse gas chromatography at low pressures

2002 ◽  
Vol 17 (2) ◽  
pp. 413-422 ◽  
Author(s):  
J. Rubio ◽  
F. Rubio ◽  
J. L. Fierro ◽  
M. C. Gutierrez ◽  
J. L. Oteo
Keyword(s):  
Gas Chromatography ◽  
Free Energy ◽  
Carbon Fiber ◽  
Energy Distribution ◽  
Surface Free Energy ◽  
Carbon Fibers ◽  
Inverse Gas Chromatography ◽  
Distribution Functions ◽  
Acid Base ◽  
Energy Distribution Functions

Carbon fiber surfaces were analyzed by inverse gas chromatography (IGC) and x-ray photoelectron spectroscopy (XPS). IGC measurements were carried out at infinite and finite dilution by using neutral and specific probes. At infinite dilution the dispersive component of the surface free energy and the acid–base indexes were obtained. At finite dilution the energy distribution functions were calculated. Three carbon fibers were analyzed, one untreated and two fibers treated with different sizings. The fibers have similar dispersive components of surface free energy but their acid–base characteristics are markedly different. The untreated fiber has an acidic surface, and the sized fibers have a surface with high base character. The energy distribution functions show different peaks assigned to active sites existing on the carbon fiber surfaces. The use of acid or basic probes provides different energy distribution functions with good correlation with the base and acid character of the fiber surface. Changes in surface heterogeneity revealed by energy distribution functions were correlated also with surface chemical composition derived from high-resolution XPS measurements.

Surface Free Energy Change of UV Exposed Composites and Coatings via Acid-Base Interactions

2011 ◽  
Author(s):  
R. Asmatulu ◽  
M. Ghaddar
Keyword(s):  
Free Energy ◽  
Service Life ◽  
Surface Energy ◽  
Surface Free Energy ◽  
Uv Light ◽  
Free Energy Change ◽  
Energy Change ◽  
Acid Base ◽  
Coating Materials ◽  
Base Interaction

Surface free energy of composite and coatings are critically important for the performance of the materials since the change in surface free energies can drastically affect the physical, chemical and physicochemical properties, and hence the service life of them. The characterization of the surface free energy is the key issue to understand the mechanisms of the surface degradation. Acid-base interaction is one way of determining the surface free energy change on these surfaces. In the present study, we exposed composite and coating surfaces to UV light, and then measured the contact angle values using various liquids (e.g., DI water, diiodomethane and glycerol). Using the van Oss approach, we calculated the surface energy changes of the surfaces exposed to the UV light. We found that the surface energy, acidity and basicity of the composite and coating materials were drastically changed as a function of UV exposure time. This study can be useful for the moisture uptake of composites, composite degradation, aging and service life of these products.

Inverse Gas Chromatography Study on London Dispersive Surface Free Energy and Electron Acceptor–Donor of Fluconazole Drug

2017 ◽  
Vol 62 (7) ◽  
pp. 2090-2094 ◽  
Author(s):  
Praveen Kumar Basivi ◽  
Visweswara Rao Pasupuleti ◽  
Ramanaiah Seella ◽  
Madhusudana Reddy Tukiakula ◽  
Subramanyam Reddy Kalluru ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Free Energy ◽  
Surface Free Energy ◽  
Electron Acceptor ◽  
Inverse Gas Chromatography ◽  
Dispersive Surface Free Energy
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