Plasma based ion implantation of engineering polymers

An overview of the rapidly developing field of modification of engineering polymers by plasma based ion implantation (PBII) and plasma based ion implantation and deposition (PBII&D) is presented. Furthermore, the applicability and usefulness of the approach of design of experiments is demonstrated by the nitrogen PBII treatments of polyamide 6 (PA) and poly(bisphenol A carbonate) (PC). Alterations in surface chemical composition and bonding were studied by XPS. Modifications in surface mechanical and tribological properties were followed by dynamic depth-sensitive nanoindentation and multiple nanoscratch measurements. Changes in wettability, surface energy and its components were evaluated by contact angle studies. Alterations in surface electrical resistance were also determined. Surface compositional changes reflected a relative decrease in the C-content and increase in the N-content for both polymers, while alterations in the peak shapes suggested degradation of the amide group with the formation of imine, protonated amine and urethane-like moieties for PA, and degradation of surface carbonate groups with the formation of imine, tertiary amine and amide-like groups for PC. The hydrophilicity of the surface increased and the surface electrical resistance decreased significantly for both polymers. The volume loss, obtained by the multi-pass scratch test, decreased from the original value expressed as V-o=100%, down to V=11% and 59% for PA and PC, respectively. For PA the incorporation of some N had a favorable effect on the resistance to abrasive wear, but an excessive amount of N decreased this effect. Similarly, for PC a significant increase of the wear resistance could not be reached by the mere increase of the total N-content, but the surface concentration of tertiary amine type N should be maximized. The latter showed positive correlations with the fluence and the fluence rate applied. (C) 2009 Elsevier B.V. All rights reserved.