The Evaluation of Gas Diffusion Electrodes by the Thermal Analysis

Abstract

We have already measured the performance and the physical property by some methods to evaluate some gas diffusion electrodes for chlor-alkali electrolysis. In this paper, we studied about the ability to evaluate the gas diffusion electrodes by thermal analysis. We prepared the powder and the seat before hot-press and after hot-press. These were made from polytetrafluoroethylene (PTFE) and from the material (GSP) of the gas-supplying layer that was mixed carbon black and PTFE. We prepared some samples of GSP that had difference of PTFE dispersion. We used the differential scanning calorimetry (DSC) and measured the heat change of fusion of PTFE in all samples. The heat change of fusion of PTFE powder was 70 J/g. On the other hand, that of PTFE sheet after hot-press was smaller than 25 J/g, may be due to the combination of PTFE by hot-press at 350°C. In a case of GSP, the heat change of fusion of the GSP sheet after hot-press was the smallest, probably because this one had much interaction between carbon black and PTFE. The heat change of fusion of GSP 1 that prepared by no flocculation process of PTFE and that PTFE was distributed homogeneous in sheet was the lowest 5.65 J g, may be due to the higher interaction between carbon black and PTFE. Consequently, it was possible to evaluate the inner structure of the electrode by DSC.