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-diam inohexane based counterparts were also studied. PA 4.12, and in particular PA 4.10, proved to have a very beneficial combination of T-m, crystallizati on 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 mak e an energetically favourable chain fold upon crystallization: isomers havi ng two possible ways of chain folding have T(m)s which are 13-15 degrees C lower than isomers having only one possible way of chain folding upon cryst allization.