INFLUENCE OF IMPLANTATION OF HEAVY METALLIC-IONS ON THE MECHANICAL-PROPERTIES OF 2 POLYMERS, POLYSTYRENE AND POLYETHYLENE TEREPHTHALATE

Ion implantation of polyethylene terephthalate (PET) and polystyrene ( PS) with various high energy metallic ions at 70 kV and a dose of 3 x 10(16) ions/cm(2) has been made. Measurements of the mechanical proper ties of the polymers before and after implantation have been made with an ultra microindentation system using both pointed and a small (2 mu m) radius spherical-tipped indenter. The surface regions were also in vestigated by atomic force microscopy (AFM) and Rutherford backscatter ing (RBS). Significant differences have been observed between the Ti-B dual-implanted surfaces and those of the Au and W implanted surfaces. For both the PET and PS, the resistance to indenter penetration at ve ry low loads was much greater for the Ti-B dual-implanted surfaces, Th e estimated maximum hardness and modulus of the implanted materials we re 0.3 and 8 GPa for the PET material and 1.4 and 16 GPa for the PS ma terial. The results obtained with the spherical indenter show a gradua l decline in effective modulus of the surface with penetration depth, whereas the hardness or contact pressure goes through a maximum before declining asymptotically to the bulk values. The values of hardness e stimated for the spherical-tipped indenter are somewhat more conservat ive than the optimistic estimates with the Berkovich indenter. The imp roved increase in hardness for the Ti-B dual-implanted PET material sc ales with the RBS measured increased depth of implantation.