High Impact Properties of Polyketone/Polyamide-6 Alloys Induced by Characteristic Morphology and Water Absorption

Nagata et al. recently developed high-impact polyketone/polyamide-6 (PK/PA) alloys and investigated their mechanical properties (Nagata et al. Polym. Prep. Jpn. 2006, 55, 4286−4287). This paper presents the results of investigations of their morphology, such as the domain size of PA and PK, features of crystalline phase of PK (the long period and thickness of lamellae are deduced), and the change in crystalline form of PA in the PK/PA alloys, using solid-state nuclear magnetic resonance (NMR), small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). Solid-state ¹³C and ¹⁵N NMR results revealed that the γ crystalline phase of PA changes into a thermodynamically stable α crystalline phase after alloying with PK. The difference in the long period of lamellae of PK/PA alloys between dry and wet conditions is discussed. We conclude that the characteristic morphology of PK and humidity of the amorphous phase of PA in the wet condition are very important factors enabling the PK/PA alloys to exhibit high impact resistance, high-strength, and high modulus.