SynopsisThe glass transition temperature is analyzed in polyamide systems characterized, owing to their chemical composition, by the absence of hydrogen bonds. The physical behavior exhibited by these systems is similar to that observed in conventional aliphatic polyamides, suggesting that, besides the hydrogen bonds, the amidic group itself plays a specific and important role in determining the polymer physical behavior generally and, in particular, the glass transition mechanism. It is surmised that this role is connected with the polar and rigid character of the amidic group, affecting chain-chain interactions and chain mobility.