Plasma modified Polytetrafluoroethylene (PTFE) lubrication of α-olefin-copolymer impact-modified Polyamide 66

Abstract

Tribological and mechanical properties of α-olefin-copolymer, impact-modified Polyamide 66, containing pristine and plasma treated Polytetrafluoroethylene (PTFE) micro-powders as solid-lubricants have been investigated. The PTFE powders were subjected to low pressure 2.45GHz microwave plasma treatment with H2 and NH3 as the process gases to aid their dispersion in PA66. Formation of polar surface groups in conjunction with significant defluorination was observed for both H2 (F/C atomic ratio 1.30) and NH3 (F/C atomic ratio 1.13) plasma treated powders. The H2 PTFE-impact modified PA66 composites exhibited a 25% increase in their impact energy absorption capabilities (25.0J) than their pristine counterparts (20.0J), along with a significant reduction of the specific wear rate at higher pv-values. At the pv-value of 6MPam/s, the specific wear rates for composites containing hydrogen plasma treated PTFE and nitrogen plasma treated PTFE were reduced by 33% (0.7×10−6mm3/Nm) and 50% (0.6×10−6mm3/Nm), respectively, as compared to pristine PTFE–α-olefin PA66 composites (1.1×10−6mm3/Nm); while showing similar coefficient of friction values. The use of plasma functionalized PTFE powders thus provides a facile route for the production of impact modified PA66 compounds with significantly lower coefficient of friction and higher wear resistance for applications like bearings and sliding elements where impact strength as well as good tribological properties are required.