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Modification of polyethylene with high energy ions and electrons. Structural, micromechanical and dielectric studies of the surface layer.
|Dariusz M. Bielinski 1, Czesław Ślusarczyk 2, Jacek Jagielski 3,4, Piotr Lipiński 1
1. Technical University of Łódź, Faculty of Chemistry, Institute of Polymer and Dye Technology (PŁ), Stefanowskiego 12/16, Łódź 90-924, Poland
Engineering applications of polyethylene is limited due to its low mechanical durability and wear resistance. Increase of the degree of crystallinity or crosslinking of polymer is not always effective, due to associated increase of its brittleness. This observation makes the modification to be limited to the surface layer of material. Application of ions and electrons for bombardment of the surface of high density (HDPE) or ultra high molecular weight (UHMWPE) polyethylene produces significant changes to the materials in the range of depth not exceeding some hundreds of nanometers. The paper presents nanoindentation data for HDPE and UHMWPE. Hardness and mechanical modulus generally increase due to ion bombardment. The effect is the higher the lower the mass of nanoparticles used, however diminishes for electrons. Figure 1 confirms that HDPE differs from UHMWPE according to interactions with a beam. The data is discussed from the point of view of structural modification of materials, studied by Grazing Incidence X-Ray Diffraction (GIXRD) and dielectric measurements. Degree of crystallinity of the surface layer of polyethylenes increases due to bombardment with light He+ ions, whereas remains constant when heavy Ar+ ions are applied. Thickness of crystallites practically does not change in both cases. The surface conductivity of the polymers studied significantly increases due to Ar+ ions treatment, whereas the effect is less pronounced for He+ ions and starts for higher beam densities. It suggests that modified layer for the latter is created in the subsurface of materials, gradually propagating towards the surface.
Presentation: Oral at E-MRS Fall Meeting 2006, Symposium D, by Dariusz M. Bielinski
See On-line Journal of E-MRS Fall Meeting 2006
Submitted: 2006-04-03 12:00 Revised: 2009-06-07 00:44