Study On The Surface Properties Of Polyolefin Nanocomposite By Scanning Probe Microscope

In recent years, the nanocomposite material appears as a new kind of material. Based on excellent mechanical and dielectric properties, it has been used widely. When the size of the nano-particles minishes to a certain degree, many microscopic effects will occur and properties of materials will be changed in the macroscopic aspect. Gradually, detection method of nanocomposite is also transformed from traditional macrosapic aspect to the range of nano-scale. The advantage of scanning probe microscopes has the high resolution and can be operated in the atmospheric environment. For those reasons, SPM can be able to measure directly. Especially in tapping mode, we can obtain not only three-dimensional morphology of the sample surface but also electrical properties. Therefore, scanning probe microscopy has played a significant role in many disciplines.In this article, surface properties of polyoefin and its nancomposite are studied by AFM. At first, we analyse the crystalline and amprphous region of polyethylene which based on the morphology characteristic of polypropylene. Secondly, Al2O3and ZnO particles are dispersed in the polypropylene matrix and make films with thickness about20μm. Use atomic force microscopy to characterize the surface topography where belong to crystalline/amorphous region and analyse the morphology characteristic in frequency spectrum by the method of power spectral density. Besides, according to the AFM-phase images, the threshold of the phase angle can obtain the crystallinity of the polymer.In this thesis, ZnO nano-particle composite polyethylene material istested. The accumulative charge is different between the nanoparticle and the matrix on the surface. And the differences can be detected by EFM. Because of the relationship of the quadratic function between the tanθ and the tip voltage, the curve coefficient is proportional to the dielectric coefficient of the sample. So, the tip voltage is changed according to certain rules and quadratic curve is described by value of tanθ. Quadratic coefficients which can obtain the change of dielectric constant with or without nanoparticle are compared and analyzed.