Thermal decomposition studies of Schiff‐base‐substitute polyphenol–metal complexes

The thermal behaviors of 2,3‐bis[(2‐hydroxyphenyl)methylene] diaminopyridine, oligo‐2,3‐bis[(2‐hydroxyphenyl)methylene] diaminopyridine, and some oligo‐2,3‐bis[(2‐hydroxyphenyl) methylene] diaminopyridine–metal complexes were studied in a nitrogen atmosphere with thermogravimetric analysis, derivative thermogravimetric analysis, and differential thermal analysis techniques. The decompositions of oligo‐2,3‐bis[(2‐hydroxyphenyl) methylene] diamino pyridine–metal complexes occurred in multiple steps. The values of the activation energy ( E ) and reaction order of the thermal decomposition were calculated by means of several methods, including Coats–Redfern, Horowitz–Metzger, Madhusudanan–Krishnan–Ninan, van Krevelen, Wanjun–Yuwen–Hen–Cunxin, and MacCallum–Tanner on the basis of a single heating rate. The most appropriate method was determined for each decomposition step according to a least‐squares linear regression. The E values obtained by each method were in good agreement with each other. It was found that the E values of the complexes for the first decomposition stage followed the order E OHPMDAP–Ni > E OHPMDAP–Cd > E OHPMDAP–Cu > E OHPMDAP–Fe > E OHPMDAP–Zn > E OHPMDAP–Co > E OHPMDAP–Cr > E HPMDAP > E OHPMDAP . © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013