Processing and structural properties of in situ polymerized poly(tetrafluoroethylene)/graphite fluoride composites



Novel poly(tetrafluorethylene)-based composites were polymerized in situ on the fluorinated petroleum coke as graphite fluoride microparticles. This allows providing high adhesion between poly(tetrafluorethylene) and filler particles which is of much important to improve sufficiently mechanical properties of the polymer. The present work aimed at investigating the relationships between mechanisms of polymerization kinetics and structural properties of the composites. In the presence of fluorinated coke, the polymerization kinetics of tetrafluorethylene, started at the surface of the filler, is characterized by a long induction period followed by the explosive growth rate. This effect was supposed to be originated by the particles exfoliation due to the anchoring of growing polymer chains to the accessible interface of the filler. Scanning electron microscope confirmed this hypothesis showing fragmentation of graphite fluoride microparticles. The resulting fragments are show to be well distributed in the polymer matrix. Wide-angle X-ray diffraction experiments demonstrates that graphite fluoride crystals are still present after polymerization of poly(tetrafluorethylene) without modification of the crystalline peak (001) position. This asserts that no overall exfoliation mechanism of graphite fluoride into (CF)n monolayers is active during the in situ polymerization. POLYM. ENG. SCI., 53:2549–2555, 2013. © 2013 Society of Plastics Engineers