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Molecular Weight Segregation on Surfaces of Polyethylene Blended Films as Estimated from Nanoscratch Tests Using Scanning Probe Microscopy

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journal contribution
posted on 22.05.2007, 00:00 by Jun-ichi Suwa, Masaki Kakiage, Takeshi Yamanobe, Tadashi Komoto, Hiroki Uehara
Nanoscratch tests using scanning probe microscopy (SPM) were performed on films prepared from two polyethylene (PE) materials polymerized by using a metallocene catalyst system with different molecular weights (MWs). Blended samples were prepared by dissolving both PE materials at various ratios in hot p-xylene. The pure and blended samples were compression molded into films at 180 °C for different holding times in the molten state. The results of SPM nanoscratch tests with an applied load of 30 nN indicated that the lower-MW surface could be easily plowed with wear debris but the higher-MW surface was less deformed. However, the deformation pattern of the blended film surface was similar to that of the lower-MW surface. These results suggest that MW segregation occurs during holding in the molten state as lower-MW components rise to the film surface.