Fluorination deposition on carbon nanofibers by PTFE decomposition as a facile method to enhance dispersion and interaction in PVDF composites

Abstract

A facile method for surface modification of nanofillers was developed in order to improve interfacial interaction and dispersion within poly (vinylidene fluoride) (PVDF) matrix. Rather than using the more conventional toxic fluorine gas method of treating nanofillers, a new method of depositing a fluorination coating from decomposition of polytetrafluoroethylene (PTFE) on a carbon nanofiber (CNF) surface was developed. The primary process parameters such as CNF/PTFE ratios and processing temperatures were studied through FTIR and morphological analysis. The fluorination coated CNFs (f-CNFs) were prepared successfully under the conditions of the CNF/PTFE ratio of 1 : 5 at 460 °C. The morphological evidence showed that the enhanced dispersion of the f-CNFs and interfacial bonding with PVDF matrix were efficiently induced by the easily manipulated surface modification method. The coating effect for the CNFs was also clearly demonstrated from the electrical conductivity results by comparison of the nanocomposites with f-CNFs and as-received CNFs. Dynamic mechanical analysis results indicated that due to the surface coating on the CNFs, the contribution of the f-CNFs to the storage modulus was dramatically increased from ∼120 MPa to 1000 MPa at −90 °C, an increase by a factor of about 8 times. This study confirmed that the new surface coating method provides a simpler way for practical modification of nanofillers, i.e. through decompositions of polymers, for treatment of nanofillers.