Structure dependence of water vapor permeation in polymer nanocomposite membranes investigated by positron annihilation lifetime spectroscopy

Correlation between microstructure and properties of graphene oxide/waterborne polyurethane composites investigated by positron annihilation spectroscopy

“…25 This maybe explained as that the WPU chain has a lower crystalline ability than PVA, which can not effectively restrict the increase of the mean size of cavity caused by agglomeration of GO nanosheets. 13,22 As show in Fig. 3b, I 3 decrease with increasing GO content, indicating a decrease in concentration of free volume in the composites, which is similar to the results of PC/RGO composites reported by Zhong and co-workers.…”

“…Positron annihilation lifetime spectroscopy was carried out by a conventional fast-fast coincidence spectrometer at room temperature. The positron source 22 Na was sandwiched between two samples with a thickness over 1 mm. One million counts were recorded for each spectrum, which was resolved into three components by a commonly used positron annihilation tting program.…”

“…The positron annihilation lifetime spectroscopy (PALS) is a helpful tool to probe the atomic scale defects, free volume and relative free volume fraction (f r ) for a wide variety of polymer nanocomposites. 21,22 The positron originate from a radioactive Na are injected into polymer matrix, and get thermalized rapidly by losing energy. Then, the thermalized positron diffuse in the polymer, annihilating directly with electrons or indirectly by forming positronium (Ps, a bound state of e + and e À ).…”

Influenceof Vinyl Acetate Content on the Surface Hydrophobic Recovery of Ethylene Vinyl Acetate Copolymer after Plasma Modification

“…This relaxation is usually evaluated by free volume which can be probed positron annihilation lifetime spectroscopy. In fact, positron annihilation has been applied as a powerful technique to probe the hole structure of materials at molecular level which is related to the material performance, such as phase separation, compartmentalization of metalcatalysts in composite matrices, vapor permeation …”

Temperature Dependence of the Pore Structure in Polyvinylidene Fluoride (PVDF)/Graphene Composite Membrane Probed by Electrochemical Impedance Spectroscopy

“…Various characterization techniques have been successfully applied to investigate the membrane structures such as SEM [7,8], TEM [9,10], porometric detection [11,12], AFM [13,14], and positron annihilation [15,16]. The information about pore structures can be directly or indirectly obtained through the above techniques.…”