Enamels Glass transition

DSC thermograms of the crosslinked enamels revealed onset of glass transitions (Tg) ranging from 15° to 35° for all three types of enamels. Attempts to detect first order transitions in the DSC corresponding to Tm or Ti were unsuccessful due to large exotherms starting at about 90°. An odd-even pattern was not observed. 

Observed Tg s vary from -123°C for polyfdimelhyl siloxane) (1-43) to 273°C for polyhydantoin (11-2) polymers used as wire enamels and to even higher temperatures for other polymers in which the main chain consists largely of aromatic structures. This range of behavior can be rationalized, and the effects of polymer structure on Tg can be predicted qualitatively. Since the glass-to-rubber transition... 

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