Miscibility in blends of aliphatic polyamides and an aromatic polyamide, nylon 3Me6T

Calorimetric and morphological investigations of blends of nylon 6 containing an amorphous aromatic polyamide, nylon 3Me6T, have shown them to be miscible across the entire range of composition. Amorphous blends illustrate the familiar monotonic and concave dependence of Tg upon composition which correlates well with existing theory. Crystallization of the nylon 6 component has been found to occur upon annealing, which is also accompanied by an unusual broadening of the glass transition in blends in the middle of the composition range. This phenomenon has been ascribed to a morphologically imposed heterogeneous distribution of the amorphous polyamide in the resultant mixed amorphous phase. Optical transmission microscopy has revealed a continuous spherulitic texture within the crystallized blends which confirms the absence of any critical solution behaviour. Preliminary investigations of the solution behaviour of nylon 3Me6T in nylons 4, 46, 66, 69, 610, 612, 11 and 12, respectively, indicate a correlation between miscibility and the relative abundance of amide functionalities of the latter. It is proposed that the behaviour observed is amenable to interpretations based upon a mean-field binary interaction model.