FTIR sorption/permeation apparatus
The newly constructed apparatus allows measuring of sorption of organic vapour mixture in polymers and also measuring of permeability of mixtures formed by gases and organic vapours. The apparatus contains sorption cell and permeation cell which are connected with gas cell. Composition of gaseous phase is analyzed by infrared spectrometer (Nicolet iS10) in the gas cell. Volume of gas cell is equal to 200 cm3 and optical path amounts 2 m. The spectrometer is provided by sensitive MCT/A detector cooled by liquid nitrogen. Spectral range of spectrometer is from 7800 to 350 cm-1 at resolution 0.5 cm-1. The sorption cell contains magnetic stirrer which allows circulation of gaseous mixture between sorption cell and the gas cell of the spectrometer. The circulation ensures homogenous constitution of gaseous mixture in whole sorption part of apparatus. Optimal frequency of magnetic stirrer is 600 rpm. Principle of estimating of sorption is measuring of absorbance decrease at wavenumber which is characteristic for the analyzed component. Estimating of permeability is based on measuring of absorbance increase in gas cell at charakteristic wavenumber.