ABSTRACT: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 PKrich phase. Moreover, the interaction and mobility of PK and PA molecular chains were investigated by using a 13 C 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.

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We have already represented that high impact mechanism of polyketone/polyamide alloy (PK/PA) is enhanced by the moisture absorption. It was thought the high impact mechanism depends on ductility caused by the moisture absorption of the alloy. This time we have investigated the nano-meter level phase separation structure of PK/PA alloys by using a TEM, an EELS and a 3D-TEM observation. It is found that the PK rich phase and the PA rich one form their co-continuous structure. Surprisingly, the three-dimensional lamella network structure is extended in the PK rich phase. Next, we have carried out SAXS measurements to evaluate lamella network structure. Moreover, the interaction and the mobility of PK and PA molecular chain of the wet and dry polymer alloy have been investigated by using solid-state high resolution NMR techniques. It was found that the moisture absorption enhances the molecular mobility of PA, and flexibility is given to the polymer alloy. The above-mentioned results revealed that the co-continuous structure and the higher-order structure are closely related to the impact properties.

Polarity-controlled ZnO thin films grown on different buffer layers were investigated as nonlinear optical materials for second harmonic generation. The effective nonlinear optical coefficient (deff) of ZnO grown on Cr-compound buffer layers showed a higher value than that of ZnO grown on MgO buffer layers. The correlations among the grain size and surface roughness with the values of deff were found to be strong. The deff of the ZnO film increased with decrease in the grain size and surface roughness. This relationship could be explained by the increase in reaction interface and the decrease in scattering probability at the surface as decrease in grain size and surface roughness, respectively.