TY - JOUR
T1 - Low-pressure H2, NH3 microwave plasma treatment of Polytetrafluoroethylene (PTFE) powders
T2 - Chemical, thermal and wettability analysis
AU - Hunke, Harald
AU - Soin, Navneet
AU - Shah, Tahir H.
AU - Kramer, Erich
AU - Pascual, Alfons
AU - Karuna, Mallampalli Sri Lakshmi
AU - Siores, Elias
PY - 2015/4/28
Y1 - 2015/4/28
N2 - Functionalization of Polytetrafluoroethylene (PTFE) powders of ~6 μm particle size is carried out using low-pressure 2.45 GHz H2, NH3 microwave plasmas for various durations (2.5, 10 h) to chemically modify their surface and alter their surface energy. The X-ray Photoelectron Spectroscopy (XPS) analyses reveal that plasma treatment leads to significant defluorination (F/C atomic ratio of 1.13 and 1.30 for 10 h NH3 and H2 plasma treatments, respectively vs. 1.86 for pristine PTFE), along with the incorporation of functional polar moieties on the surface, resulting in enhanced wettability. Analysis of temperature dependent XPS revealed a loss of surface moieties above 200 °C, however, the functional groups are not completely removable even at higher temperatures (>300 °C), thus enabling the use of plasma treated PTFE powders as potential tribological fillers in high temperature engineering polymers. Ageing studies carried over a period of 12 months revealed that while the surface changes degenerate over time, again, they are not completely reversible. These functionalised PTFE powders can be further used for applications into smart, high performance materials such as tribological fillers for engineering polymers and bio-medical, bio-material applications.
AB - Functionalization of Polytetrafluoroethylene (PTFE) powders of ~6 μm particle size is carried out using low-pressure 2.45 GHz H2, NH3 microwave plasmas for various durations (2.5, 10 h) to chemically modify their surface and alter their surface energy. The X-ray Photoelectron Spectroscopy (XPS) analyses reveal that plasma treatment leads to significant defluorination (F/C atomic ratio of 1.13 and 1.30 for 10 h NH3 and H2 plasma treatments, respectively vs. 1.86 for pristine PTFE), along with the incorporation of functional polar moieties on the surface, resulting in enhanced wettability. Analysis of temperature dependent XPS revealed a loss of surface moieties above 200 °C, however, the functional groups are not completely removable even at higher temperatures (>300 °C), thus enabling the use of plasma treated PTFE powders as potential tribological fillers in high temperature engineering polymers. Ageing studies carried over a period of 12 months revealed that while the surface changes degenerate over time, again, they are not completely reversible. These functionalised PTFE powders can be further used for applications into smart, high performance materials such as tribological fillers for engineering polymers and bio-medical, bio-material applications.
KW - Degeneration
KW - ESCA/XPS
KW - Low-pressure microwave plasma
KW - Polytetrafluoroethylene (PTFE)
KW - Thermal stability
UR - http://www.scopus.com/inward/record.url?scp=84930665082&partnerID=8YFLogxK
U2 - 10.3390/ma8052258
DO - 10.3390/ma8052258
M3 - Article
SN - 1996-1944
VL - 8
SP - 2258
EP - 2275
JO - Materials
JF - Materials
IS - 5
ER -