Change in Surface Microstructure and Properties of PTFE after Solar Radiation and its Mechanism

Abstract

A series of solar radiation tests for the polytetrafluoroethylene(PTFE) bulk and film samples were carried out using Q-SUN XE-3-HSC type Solar Radiation Simulator, with the test parameters as follows: radiation intensity is 1 120 W/m², temperature is 55 °C and humidity is 70% RH. Surface morphology, composition and microstructure of the PTFE samples before and after radiation tests were characterized contrastively. Effect of solar radiation on the tribology and wetting properties of PTFE were also studied by tribometer and contact angle tester, respectively. The results show that, for radiated PTFE, surface roughness, the relative content of C element, the friction coefficients and the contact angle with water increased in varying degrees. In conclusion, the obvious change in PTFE samples can be mainly attributed to break of (CFx)-C bonds after bombardment of high energy UV photons, which causes the loss of F-rich groups, oxidation, crosslinking and restructuring of active unsaturated groups.

Keywords

solar radiation / PTFE / microstructure / tribological properties / wetting properties