Porometry of Porous Materials by Means of Differential Scanning Calorimeter: Thermoporometry Payman Sobhanipour, Reza CheraghiAbstract
In this paper, thermoporometry method was employed to characterize the porosity of an ultra-filtration (UF) polyacrylonitrile asymmetric membrane with macrovoids (size ~ 10-50 µm) in its sub layer. According to literatures, thermoporometry only detects nano pores with pore radius between 2 to 65 nm. Therefore, it was interesting to study the efficiency of the method in a sample including macrovoids. Endothermic melting thermograph of frozen sample temperature range: -60 to 5 °C, scan rate: 0.5 °C/min) was obtained using typical differential scanning calorimeter (DSC)
that demonstrated overlapping pore water and free water peaks. By transforming the DSC thermograph to pore size distribution curve (pore volume versus pore radius), the values of 8.19 cm
3
/g, 562.5 m
2
/g and 29.12 nm was calculated as membrane pore volume (VP), internal surface area (SP) and average pore radius (rP), respectively. The results show that the membrane wall (matrix) between macrovoids is nano porous with high internal surface area. Also, macrovoids are not sensible by thermoporometry.
Keywords: Thermoporometry, Polyacrylonitrile, Macrovoid, Ultra-filtration membrane
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