Phase Separation and Mechanical Properties of Polyketone/Polyamide Polymer Alloys

摘要

We have investigated polyketone (PK)/polyamide 6 (PA) polymer alloys having enhanced Charpy impact energy greater than that of polycarbonate (PC) as a result of moisture absorption. From the results of differential scanning calorimetry (DSC), Raman spectroscopy, and transmission electron microscope (TEM) observation of the polymer alloys, it was found that PK-rich and PA-rich phases exist at the nanometer level in the polymer alloys; however, a microscopic interaction phase formed between the two phases. 3D-TEM observations, electron energy loss spectroscopy, and small-angle X-ray scattering measurements revealed that a co-continuous nanolayer formed from the PA-rich phase and lamella network of the PK-rich phase. Moreover, the interaction and mobility of PK and PA molecular chains were investigated by using a C-13 cross polarization/magic angle sample spinning NMR technique. It was found that moisture absorption markedly enhances the mobility of PA molecular chains in PK/PA alloys. This suggests that the wet (moisture-absorbed) PA phase of PK/PA alloys allows quick deformation upon impact stimulation. On the other hand, the results of Charpy impact tests showed that the total impact energy (E-total) of the wet polymer alloy was much higher than that of the dry one. An examination of the load-displacement curves revealed that the wet samples showed a pronounced increase in displacement compared with the dry ones. From these results, it was concluded that the lamella network of the PK-rich phase sustains the maximum stress and that the large displacement of the PA-rich phase increases the impact energy.