J. Cogen, A. Hilmer
Dec 1, 2008
Citations
0
Influential Citations
7
Citations
Journal
Polymer Degradation and Stability
Abstract
Abstract The important polymer stabilizer, 1,2-bis(3,5-di- tert -butyl-4-hydroxyhydrocinnamoyl)hydrazine, which serves a dual role as a metal deactivator and antioxidant, is shown to have crystal polymorphism. Although the published melting range is 225–232 °C, which is well above the processing temperature of many polymers in which it is used, existence of a second polymorph that transforms below 205 °C is demonstrated. This α polymorph, which is thermodynamically stable at room temperature, is thermodynamically un-favored at temperatures above about 176 °C. It is shown that under some conditions the α polymorph can endothermically pass directly into the melt state at temperatures below 205 °C, while under other conditions it undergoes a direct endothermic solid–solid transition to the higher melting β polymorph. The results highlight the potential importance of polymorphs for controlling polymer additive behavior and elucidate important phenomena relevant to dispersion of this additive in polymer compounds.