THERMOANALYTICAL AND X-RAY STUDIES OF BLENDS FROM POLYAMIDE-6 AND POLYAMIDE-6,6

Thermodynamic miscibility and compatibility in the solid state of solution cast, melt cast, oriented and KI3/K2S2O3-treated samples of polyamide-6 (PA-6)/polyamide-6,6 (PA-6,6) systems was studied by means of differential scanning calorimetry (DSC) and X-ray diffraction. After iodine treatment solution cast blends show a complete solid state transition of alpha-PA-6-crystallites into their gamma-modification. In samples crystallized isothermally this transition is incomplete. After iodine treatment of quenched blends with a low content of PA-6,6 and pure PA-8 a gamma*-gamma-transition of PA-6-crystallites is found. In all other blends with a surplus of PA-6 gamma*-crystallites of PA-6 are formed during iodine treatment. In oriented samples annealed in simmering water of equal PA-6 and PA-6,6 content or a slight surplus of PA-6,6 mixed crystallites were found after iodine treatment. These mixed crystallites are found in a gamma*-modification similar to that of PA-6. The mixed crystallites melt at 503 K. Iodine treatment facilitates their formation. DSC studies of the glassy state of the blends show that the components are at least partially compatible in the solid noncrystalline regions.