Determination of structure and morphology

Membrane characterization means the determination of structural and morphological properties of a given membrane. Because membranes range from porous to nonporous depending on the type of separation problem involved, different characterization techniques are required in each case. For example, in MF or UF membranes, fixed pores are present. MF membranes have macropores (pore diameter > 50 mn), while UF membranes have mesopores (2 mn < pore diameter < 50 nm). The pore size (and size distribution) mainly determines which particles or molecules are retained or pass through. On the other hand, for dense or nonporous membranes, no fixed pores are present and the material chemistry itself mainly determines the performance. 

In 1952 James and Martin [12] replaced the liquid mobile phase with a gas phase two new chromatographic techniques were developed gas-liquid and gas-solid chromatography. This led to an unprecedented development in the analytical and preparative separation of mixtures and then, from 1969 [13,14], it allowed the determination of structure and morphology of stationary phases especially polymers and, from 1971 [15], the determination of the thermodynamic properties of polymer solutions. 

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