Akira Kishi

A new simultaneous apparatus for X-ray diffractometry and differential scanning calorimetry (XRD-DSC)

Abstract An instrument was developed for performing simultaneous X-ray diffractometric and differential scanning calorimetric (XRD-DSC) measurement using a power compensation DSC (pc-DSC). The feasibility of the technique is demonstrated by examining the thermal dehydration measurement of zinc formate dihydrate (Zn(HCO 2 ) 2 ·2H 2 O). The DSC curve shows apparent double endothermic peaks during the dehydration process, while X-ray diffraction analysis indicated that the resulting anhydrous product, Zn(HCO 2 ) 2 , was crystalline. The simultaneous measurement reveals that the DSC curve arises from a combination of the endothermic dehydration peak and the exothermic crystallization peak which resulted from the progression of the anhydrous products.

Thermogravimetry and evolved gas analysis of polyimide

Abstract TG–DTA–EGA simultaneous measurements were made for polyimide isothermally at 498 and 541°C in simulated air, in order to confirm the previously found facts by TG–DTA that below 520°C the mass loss is a single step process but above 550°C it proceeds by a two step process. All detected volatile products are carbon dioxide, carbon monoxide, water, nitrogen and nitrogen monoxide at the both temperatures, but the volatilization behavior at 541°C is different from that at 498°C, as was expected from the previous results. Thus the previous postulate was confirmed. However, because volatilization of water at 498°C differs from that of nitrogen monoxide, the process in the lower temperature range really proceeds by a two step process. On the other hand, at 541°C the volatilization rates of all products change similarly to each other and also to the mass loss curve and the DTA curve.

Thermal dehydration of cobalt and zinc formate dihydrates by controlled-rate thermogravimetry (CRTG) and simultaneous X-ray diffractometry–differential scanning calorimetry (XRD-DSC)

Abstract The thermal dehydration study of the similar hydrated salts, cobalt and zinc formate dihydrates, have been carried out successfully by means of X-ray diffractometry–differential scanning calorimetry (XRD-DSC) and controlled-rate thermogravimetry (CRTG). X-ray diffraction analysis recorded simultaneously indicates that the resulting anhydrous product, Zn(HCO2)2, was crystalline, while Co(HCO2)2 was amorphous. The XRD-DSC data are proven to be invaluable in verifying the interpretation of overlapping processes in thermal events. In addition, these differences in the resulting anhydrous products can be explained from kinetic analysis results based on the CRTG data. The kinetic mechanism governing the dehydration of zinc formate dihydrate is a nucleation and growth process, while in the case of cobalt formate dihydrate a phase boundary controlled reaction is the governing mechanism.