Polyamides 4.10 and 4.12 and their Isomers

A series of aliphatic 1, 4-diaminobutane based polyamides 4. y with y = 8, 9, 10 and 12 was synthesized and characterized. For comparison, some 1, 6-diaminohexane based counterparts were also studied. PA 4.12, and in particular PA 4.10, proved to have a very beneficial combination of T m , crystallization rate and physical properties. First indications were obtained, that for a series of aliphatic polyamide isomers, containing 16 carbon atoms in the repeating unit, the melting points are related to the number of ways to make an energetically favourable chain fold upon crystallization: isomers having two possible ways of chain folding have T m s which are 13–15 °C lower than isomers having only one possible way of chain folding upon crystallization.