Studies of the PEM Surface

Direct visualization of domain sizes and random morphology of ionomer membranes can be obtained from microscopy studies (Hiesgen et al., 2010). Information obtained from these approaches is restricted by the need to consider thin films ( 100 nm 

Crystallinity associated with the local ordering of polytetrafluoroethylene (PTFE) backbones is deemed an important PEM property in view of mechanical and thermal stability. The degree of crystallinity has an impact on microscopic stress-strain 

Crystallinity depends on the chemical composition of the ionomer. Moreover, it is affected by the thermal processing history of the PEM, the solvent used during preparation, and the membrane thickness (Kim et al., 2006 Moore and Martin, 1988). 

Neutron and x-ray diffractograms can be analyzed in view of size and shape of ordered domains, as well as the distance between crystallites. Scattering from backbone crystallites is believed to be responsible for the matrix knee in SAXS and SANS spectra at about q 0.04 A . The corresponding distance between crystallites varies in the range from 150 to 500 A. It increases with increasing PEM thickness. 

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